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CORD-19:fff6fe12beb51ee2641ddb5381378ff3560d8103 JSONTXT 9 Projects

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Id Subject Object Predicate Lexical cue
T1 0-64 Sentence denotes Health shocks and their long-lasting impact on health behaviors:
T2 65-111 Sentence denotes Evidence from the 2009 H1N1 pandemic in Mexico
T3 113-121 Sentence denotes Abstract
T4 122-246 Sentence denotes Worldwide, the leading causes of death could be avoided with health behaviors that are low-cost but also difficult to adopt.
T5 247-385 Sentence denotes We show that exogenous health shocks could facilitate the adoption of these behaviors and provide long-lasting effects on health outcomes.
T6 386-621 Sentence denotes Specifically, we exploit the spatial and temporal variation of the 2009 H1N1 influenza pandemic in Mexico and show that areas with a higher incidence of H1N1 experienced larger reductions in diarrhea-related cases among young children.
T7 622-687 Sentence denotes These reductions continue even three years after the shock ended.
T8 688-819 Sentence denotes Health improvements and evidence of information seeking via Google searches were consistent with changes in hand washing behaviors.
T9 820-882 Sentence denotes Several robustness checks validate our findings and mechanism.
T10 883-909 Sentence denotes Published by Elsevier B.V.
T11 911-1005 Sentence denotes Worldwide, the adoption of low-cost technologies could improve health outcomes and save lives.
T12 1006-1282 Sentence denotes For example, regular physical activity reduces the risk of diabetes; condoms help reduce the spread of sexually transmitted diseases, including HIV; reductions in cigarette consumption help avoid pulmonary cancer; and hand washing with soap prevents gastrointestinal diseases.
T13 1283-1397 Sentence denotes However, despite their effectiveness, the take up rates of these products or behaviors is very low (Dupas, 2011) .
T14 1398-1671 Sentence denotes For instance, while the role of hand washing as an effective way to reduce gastrointestinal diseases has been known for more than a century (Koplik, 1902) , 2 in developing countries, only 30% of household members wash their hands before preparing food or after defecation.
T15 1672-1757 Sentence denotes In some countries the rate is as low as zero (World Bank, 2005; Chase and Do, 2010) .
T16 1758-2168 Sentence denotes Moreover, intensive small-scale interventions show significant reductions in diarrhea (e.g., Ejemot-Nwadiaro et al., 2008; Luby et al., 2004; Luby et al., 2005) , 3 but scaling up similar inter-2 For example, Koplik (1902) summarizes the research of the previous decade and recommends the "scrupulously" cleaning of hands and nails ("with brush and file") after changing a diaper for nurses handling a newborn.
T17 2169-2254 Sentence denotes Mothers, he added, "should carefully cleanse their hands before feeding the baby" (p.
T18 2255-2260 Sentence denotes 321).
T19 2261-2412 Sentence denotes The rationale for this hygiene practice was also well understood "since this way contamination of the infant's food with fecal bacteria is avoided" (p.
T20 2413-2417 Sentence denotes 46).
T21 2418-2516 Sentence denotes 3 Common interventions to reduce diarrhea have focused on providing infrastructure or information.
T22 2517-2704 Sentence denotes Infrastructure projects focus on providing safe water supplies and sanitation (e.g., Pattanayak et al., 2009; Kremer et al., 2011) , micronutrients or vaccinations (Dowling and Yap 2014 .
T23 2705-2829 Sentence denotes Information-based interventions focus on hygiene education and community-led total sanitation (CLTS) (Dowling and Yap 2014 .
T24 2830-2904 Sentence denotes Also, recent papers have discussed the external validity of these studies.
T25 2905-3058 Sentence denotes See Hammer and Spears (2016) for a discussion on whether the sites where village sanitation projects take place might be likely to exhibit large effects.
T26 3059-3216 Sentence denotes http://dx.doi.org/10.1016/j.jhealeco.2017.03.008 0167-6296/Published by Elsevier B.V. ventions does not (e.g., Meredith et al., 2013; Galiani et al., 2012) .
T27 3217-3361 Sentence denotes 4 Understanding the barriers for the adoption of these preventive behaviors and products is an urgent issue in health and development economics.
T28 3362-3539 Sentence denotes A growing literature in economics is studying the role that information plays on health behaviors as a salient input in the production of health outcomes (Cawley and Ruhm 2011).
T29 3540-3755 Sentence denotes 5 In particular, an emerging conclusion suggests that the mere provision of information might not matter (e.g., smokers do know that smoking is harmful and may even overestimate the risk of smoking, Viscusi, 1990) .
T30 3756-3869 Sentence denotes Rather, the emphasis seems to be on when information alters the decision-making process (Luoto and Carman 2014) .
T31 3870-4170 Sentence denotes Our paper contributes to this literature by showing that health shocks such as disease outbreaks can operate as "natural nudges" that facilitate changes in health behaviors that lead to improvements in health outcomes, and that these types of shock-induced improvements can have long-lasting effects.
T32 4171-4556 Sentence denotes In particular, we illustrate how in Mexico, a middle-income country with near universal access to water and sanitation but where intestinal infections are the second main cause of child death and 11 percent of children under five suffer from acute diarrhea, the onset of the 2009 H1N1 influenza (swine flu) led to a large, robust and long-lasting decline in diarrhea cases of children.
T33 4557-4859 Sentence denotes This is done with a difference-in-difference framework using a balanced panel of annual state-level data aggregated from hospital discharges related to diarrhea and the total number of laboratory confirmed cases of the swine flu in Mexico derived from Mexico's Ministry of Health (Secretaria de Salud).
T34 4860-5090 Sentence denotes Relying on administrative data −where trained medical professionals register their diagnoses-and several robustness checks, we rule out the possibility that our findings are driven by misdiagnosis of either H1N1 or diarrhea cases.
T35 5091-5166 Sentence denotes Additional placebo tests and robustness checks further support our results.
T36 5167-5341 Sentence denotes For example, we find no association between diarrhea-related cases before the H1N1 outbreak (2006) (2007) (2008) and the number of confirmed swine flu cases observed in 2009.
T37 5342-5433 Sentence denotes There is also no evidence of people avoiding hospitals altogether due to the H1N1 pandemic.
T38 5434-5592 Sentence denotes Furthermore, the negative effect on diarrhea is also observed in morbidity cases beyond hospitalizations, as captured by Mexico's Annual Morbidity Statistics.
T39 5593-5799 Sentence denotes Unlike the small (and anticipated) nature of the seasonal flu, it quickly became clear that the new H1N1 strain was easily transmittable and that existing vaccines did not prevent contracting the swine flu.
T40 5800-5940 Sentence denotes Thus, people experienced an environment where the new virus was affecting a large number of individuals, and could, in some cases, be fatal.
T41 5941-6169 Sentence denotes This provides an important context to test theoretical models of health behavior where a decision to engage in preventive behavior is triggered only when the (contagious) disease crosses a high threshold (e.g., Philipson 2000) .
T42 6170-6329 Sentence denotes Consistent with such models, we find a null effect for the seasonal flu on diarrhea outcomes that contrasts with our negative and large findings from the H1N1.
T43 6330-6447 Sentence denotes Using Google searches originated in Mexico we identify an increase in the demand to learn about preventive behaviors.
T44 6448-6554 Sentence denotes Specifically, we find that searches for the word "hand sanitizer" spiked during the peaks of the pandemic.
T45 6555-6841 Sentence denotes Furthermore, we show that an 4 Other examples include Kremer and Miguel (2007) 's finding that information had no effect on Kenyans' investing in deworming treatments, and Ashraf, Berry and Shapiro (2010)'s report that information had no effect on chlorine water purification in Zambia.
T46 6842-6979 Sentence denotes 5 Other strategies include, but are not limited to, taxation, cash incentives and restrictions on use or purchase of preventive products.
T47 6980-7125 Sentence denotes See Cawley and Ruhm (2011) for an extensive discussion of policy options and theoretical models related to risky behaviors in advanced economies.
T48 7126-7253 Sentence denotes For developing countries, a growing literature explores the role of subsidies on the adoption of health products and behaviors.
T49 7254-7401 Sentence denotes See Dupas (2011 Dupas ( , 2014 ) for a review. increase in the incidence of the H1N1 is associated with more searches for this preventive behavior.
T50 7402-7523 Sentence denotes Other mechanisms, such as the role of government expenditure and health infrastructure, do not seem to play a major role.
T51 7524-7666 Sentence denotes Further incidence of the H1N1 after 2009 allows us to test whether such "reminders" continue to have an impact on health outcomes beyond 2009.
T52 7667-7789 Sentence denotes Using an event study we show that the contemporaneous negative effect is observed in 2009 and 2010 but disappears by 2012.
T53 7790-7970 Sentence denotes However, when testing for the persistence of the 2009 shock, we find that this effect dominates the contemporaneous impact suggesting long-lasting consequences of the larger shock.
T54 7971-8145 Sentence denotes This is an important result because, as we will show later, the evidence on whether information campaigns have long-lasting effects is scant (e.g., Cairncross et al., 2005) .
T55 8146-8351 Sentence denotes Taken together, our results provide empirical support to recent behavioral economics models where large health shocks alter the risk perceptions of individuals and affect the production of health outcomes.
T56 8352-8598 Sentence denotes In that regard, our findings are consistent with previous studies that have shown, in the case of the United States, that smokers are more likely to quit when they experience more severe health shocks (Sloan et al., 2003; Margolis et al., 2014) .
T57 8599-8862 Sentence denotes It is also consistent with the findings from Philipson and Posner (1994) , who document a rapid reduction in gonorrhea for the male homosexual community in San Francisco as a result of a change towards safer sex practices soon after the onset of the HIV pandemic.
T58 8863-8925 Sentence denotes The rest of the paper is divided into six additional sections.
T59 8926-9000 Sentence denotes We start by briefly describing the H1N1 outbreak in Mexico in section two.
T60 9001-9068 Sentence denotes Section three describes the data sources and our econometric model.
T61 9069-9150 Sentence denotes The main results, including our robustness checks, are presented in section four.
T62 9151-9256 Sentence denotes Section five describes the possible mechanisms while section six examines the persistence of the effects.
T63 9257-9432 Sentence denotes Section seven summarizes our findings, discusses policy implications as well as the way our paper expands our understanding of the production of health outcomes and concludes.
T64 9433-9621 Sentence denotes In March and early April 2009, Mexico experienced an outbreak of respiratory illnesses which was later confirmed to have been caused by the novel influenza A(H1N1) 2009 virus or swine flu.
T65 9622-9743 Sentence denotes 6 The H1N1 is a contagious virus transmitted via droplets from coughs and sneezes or by interacting with infected people.
T66 9744-9865 Sentence denotes This influenza virus can survive on environmental surfaces such as kitchen counters and door knobs for up to eight hours.
T67 9866-9940 Sentence denotes H1N1 shares many of the symptoms of the seasonal flu: fever, cough, aches.
T68 9941-10124 Sentence denotes However, while it is rare to have gastrointestinal symptoms from the seasonal flu, some cases of the swine flu, around 13 percent, exhibited nausea, vomiting or diarrhea (SSA, 2011) .
T69 10125-10231 Sentence denotes The World Health Organization (WHO) declared the 2009 H1N1 outbreak as the first flu pandemic in 41 years.
T70 10232-10430 Sentence denotes As of June 2011, Mexico's Ministry of Health reported that there were more than 70,000 confirmed cases of swine flu in 2009, including more than one thousand deaths and around 2400 hospitalizations.
T71 10431-10596 Sentence denotes Most of the confirmed H1N1 cases in Mexico involved a relatively younger cohort, aged 10-39, compared to the population typically affected by the seasonal influenza.
T72 10597-10718 Sentence denotes The incidence of these cases was highest in May, June, and September of 2009 (Appendix Fig. 1 in Supplementary material).
T73 10719-10867 Sentence denotes All states in Mexico were affected by the swine flu outbreak, but there was variation in the distribution of cases across states (Fig. 1, Panel A) .
T74 10868-10992 Sentence denotes This distribution does not coincide with the spatial pattern observed for diarrhea cases prior to 2009 (Panel B of Fig. 1 ).
T75 10993-11221 Sentence denotes The announcement of the first case of H1N1 on April 23, 2009, was followed by a series of other actions coordinated by the Mexican government, including the Ministry of Health, and other national and international organizations.
T76 11222-11478 Sentence denotes These actions included enactment of the National Pandemic Preparedness and Response Plan which coordinated and implemented risk communication strategies to promote respiratory hygiene and to maintain the public informed about the transmission of influenza.
T77 11479-11594 Sentence denotes TV and radio ads, a dedicated hot line, alert text messaging, and social media messaging were launched on April 25.
T78 11595-11817 Sentence denotes The goal of the campaign was to educate the public about frequent and proper hand washing techniques, covering sneezes or coughs, using face masks and hand sanitizers, seeking care if ill, and discouraging self-medication.
T79 11818-12110 Sentence denotes The Ministry of Health and the Office of the President coordinated with media outlets to provide daily updates on the number of confirmed cases, which was reflected on substantial coverage on the number of confirmed cases in each state as well as key messaging on how to prevent transmission.
T80 12111-12239 Sentence denotes On April 26, the World Bank lent $25 million for immediate aid and $180 million in long-term assistance to address the outbreak.
T81 12240-12341 Sentence denotes The announcement of the World Bank aid was followed by the closure of schools nationwide on April 27.
T82 12342-12575 Sentence denotes On April 30, the Mexican government declared that all "non-essential" activities be suspended and implemented social distancing measures that closed restaurants, entertainment venues, and cancelled large public gatherings nationwide.
T83 12576-12897 Sentence denotes Throughout the development of the outbreak, the World Health Organization actively updated their assessment from "event of international concern" on April 24 to pandemic phase 4 (sustained community transmission) on April 27, to phase 5 (imminent pandemic underway) on April 29, and then to phase 6 (pandemic) on June 11.
T84 12898-12987 Sentence denotes Although the pandemic was still underway, activities began to return to normal in Mexico.
T85 12988-13036 Sentence denotes By May 11, most schools had reopened nationwide.
T86 13037-13227 Sentence denotes Parents and volunteers coordinated with school and health authorities to sanitize the schools with cleaning supplies paid for by the federal government before the schools reopened on May 11.
T87 13228-13379 Sentence denotes In addition, parent-volunteers screened students in elementary schools to identify and send home students reporting or showing influenza-like symptoms.
T88 13380-13527 Sentence denotes It is unclear how long the screeners were in place, but there are reports that screeners in schools were only present for a few days (SSA, 2009a) .
T89 13528-13764 Sentence denotes Additional collaboration at the state, local, and international level also occurred to disseminate information in the workplace, public transportation, and local communities, although the details are too varied for us to summarize here.
T90 13765-13863 Sentence denotes There were other waves of cases in June and September, but they were reported to be under control.
T91 13864-14067 Sentence denotes Appendix Table 1 in Supplementary material provides further details about measures taken by the Mexican government and other organizations in the first months following the first confirmed cases of H1N1.
T92 14068-14231 Sentence denotes Thus, while the swine flu remains in Mexico today, none of the following years had the same level of intensity, awareness and possible "panic" as observed in 2009.
T93 14232-14456 Sentence denotes In the next section we describe our data and how we exploit the variation across time and space to identify the causal impact of an exogenous shock that induced changes in behavior and ultimately reduction in child diarrhea.
T94 14457-14614 Sentence denotes We use several data sources for this paper, all but one, collected by Mexico's Ministry of Health (Secretaria de Salud) to create a stateyear balanced panel.
T95 14615-14679 Sentence denotes First, we use hospital discharge data from all public hospitals.
T96 14680-14878 Sentence denotes For the purpose of this study we use data for the 2006-2012 period and we aggregate the discharges at the year and state level to match the source of the time and spatial variation in the H1N1 data.
T97 14879-15067 Sentence denotes 7 Common to many developing countries, the public hospital system covers most of the population and in the case of Mexico, 85 percent of all hospital visits are covered by these hospitals.
T98 15068-15140 Sentence denotes 8 This large coverage strengthens the external validity of our findings.
T99 15141-15464 Sentence denotes 9 A key advantage of this dataset is that the coding for the primary diagnosis of the discharge follows the International Statistical Classification of Diseases and Related Health Problems 10th Revision or ICD-10, created by the World Health Organization (WHO, 2010) , where the treating physician determines the diagnosis.
T100 15465-15751 Sentence denotes Relying on the report of a trained professional represents a significant improvement in the literature as it helps reduce the recall bias and other measurement errors that plague self-reported data obtained from household surveys (Heady 2016) and improves the accuracy of the diagnosis.
T101 15752-15890 Sentence denotes The coding included in the database comes from the actual diagnosis regardless of the initial reason that led the patient to the hospital.
T102 15891-16195 Sentence denotes 10 Furthermore, the use of hospital discharge data implies that we are focusing on the extreme and treated cases of diarrhea (i.e., those severe enough that resulted in a hospital visit and even death) as opposed to those cases that were either treated at local health centers, at home or went untreated.
T103 16196-16412 Sentence denotes Following Mexico's Ministry of Health's definition of "acute infectious diarrhea" we consider cases where the primary diagnosis was an intestinal infection as classified by ICD-10 codes A00 through A09X (SSA, 2012) .
T104 16413-16498 Sentence denotes The details of the codes are presented in Appendix Table 2 in Supplementary material.
T105 16499-16638 Sentence denotes In Mexico, diarrheal cases in children under five represent 51 percent of all hospital discharges where the primary diagnosis was diarrhea.
T106 16639-16768 Sentence denotes 11 For this reason and following the literature of early childhood development we restrict our analysis mainly to this age group.
T107 16769-16917 Sentence denotes 12 The hospital discharge data are complemented with morbidity information collected in the Anuarios de Morbilidad 13 (Annual Morbidity Statistics).
T108 16918-17296 Sentence denotes The Anuario is a yearly report produced by the Mexican Health System that collects information from all the public and private health centers nationwide to create an Epidemiological Surveillance Bulletin for the National System of Epidemiological Surveillance or SINAVE, similar to the CDC's National Notifiable Dis-7 Data covering some public hospitals are available from 2002.
T109 17297-17471 Sentence denotes Data for all public hospitals are available beginning 2004, but we do not incorporate it into this analysis because the age variable was not consistently coded for that year.
T110 17472-17674 Sentence denotes For 2005, we do not have information of the limited rollout of the rotavirus vaccination campaign and therefore restrict the sample to 2006 onwards when the rotavirus program was nationally implemented.
T111 17675-17725 Sentence denotes 8 This dataset does not record month of admission.
T112 17726-17916 Sentence denotes This variable is only included in a dataset that, unfortunately, has a heavily restricted coverage (<50% of the national discharges) and does not represent a random sample of all discharges.
T113 17917-18006 Sentence denotes These limitations prevent us from using the month-recording dataset in our main analysis.
T114 18007-18118 Sentence denotes 9 Mexico's Ministry of Health reports that in 2009 there were 91.6 million users of the public hospital system.
T115 18119-18271 Sentence denotes However, the report does not indicate whether the reported 91.6 million users included repeat users. (Sistema Nacional de Información en Salud (SINAIS).
T116 18272-18378 Sentence denotes Población usuaria por entidad federativa según institución, 2009, Boletín de Información Estadística, Vol.
T117 18379-18540 Sentence denotes III, Servicios Otorgados y Programas Sustantivos, Numero 29, Año 2009. http://www.sinais.salud.gob.mx/publicaciones/ index.html, last accessed November 24, 2013.
T118 18541-18664 Sentence denotes 10 The primary diagnosis is determined based on the condition that was investigated and treated during the hospitalization.
T119 18665-18926 Sentence denotes It is defined as, "The diagnosed condition at the end of the event that led to the primary cause of treatment for the patient. . .if there is more than one (condition), the one that is considered to be responsible for the most use of resources must be selected.
T120 18927-19043 Sentence denotes If no diagnosis is made, the primary diagnosis is the main symptom, abnormal finding or problem" (SSA, 2010a, p.78).
T121 19044-19205 Sentence denotes 11 There were 5.8 million hospital discharges in Mexico in 2011 with a rate of 456.3 discharges per 10,000 population and 129,000 cases were related to diarrhea.
T122 19206-19366 Sentence denotes 12 Older children (5-14) represent 15 percent of all the hospital discharges diagnosed as diarrhea while people 45 and older constitute 20 percent of the cases.
T123 19367-19496 Sentence denotes 13 Available at http://www.epidemiologia.salud.gob.mx/anuario/html/anuarios. html eases Surveillance System in the United States.
T124 19497-19617 Sentence denotes The Anuarios de Morbilidad concentrates on the leading causes of morbidity rather than collecting all possible diseases.
T125 19618-19669 Sentence denotes It includes ambulatory and physician office visits.
T126 19670-19891 Sentence denotes This facilitates a weekly report of the incidence of selected diseases, where acute respiratory infections as well as gastrointestinal diseases have been consistently covered in the data throughout the period of analysis.
T127 19892-20072 Sentence denotes As in the case of the hospital discharge data, diagnoses recorded in the Anuarios de Morbilidad follow the ICD-10 classification and have been determined by a medical professional.
T128 20073-20252 Sentence denotes In addition, there is a quality assurance process that includes a multi-layer system of checks until the data are released to the public months after the end of the calendar year.
T129 20253-20379 Sentence denotes This dataset complements our hospitalization records and is available at the state level and not at the individual case level.
T130 20380-20534 Sentence denotes The third data source also comes from SINAVE and provides us with the swine flu cases −coded as J09-at the state level only, and yearly from 2009 onwards.
T131 20535-20598 Sentence denotes 14 A key advantage of this source is the quality of the report.
T132 20599-20718 Sentence denotes The swine flu cases included in the dataset have been confirmed by a laboratory as true cases of the H1N1 (SSA, 2010b).
T133 20719-20987 Sentence denotes In an effort to improve and standardize influenza surveillance, the Ministry of Health required all Mexican medical institutions to confirm suspected cases of the H1N1 with laboratory tests −a practice that continues to this day (SSA, 2010b (SSA, , 2013 (SSA, , 2014 .
T134 20988-21110 Sentence denotes This heavily limits the possibility of misclassification with other diseases that could share symptoms with the swine flu.
T135 21111-21426 Sentence denotes 15 Additional data on health expenditures by the government (state and Federal), distribution of oral rehydration salts, distribution of vaccines, and hospital infrastructure as measured by the number of hospital beds come from Mexico's Ministry of Health SINAIS (National System of Health Information) data system.
T136 21427-21465 Sentence denotes 16 We utilized two other data sources.
T137 21466-21541 Sentence denotes Child mortality due to diarrhea is obtained from Mexico's Vital Statistics.
T138 21542-21636 Sentence denotes This dataset has 100 percent coverage and includes deaths that occur at home and in hospitals.
T139 21637-21776 Sentence denotes 17 Also, we use Google Trends data as they provide an index that captures the popularity of a given Internet search across time and states.
T140 21777-21933 Sentence denotes There is a growing number of papers using data from Google searches (available as Google Trends: http:// www.google.com/trends/) to uncover economic issues.
T141 21934-22194 Sentence denotes For example, these data have been used to predict economic indicators in the United States and Germany (Choi and Varian, 2012; Askitas and Zimmermann, 2009; D'Amuri and Marcucci, 2010) as well as discrimination and voting behavior (Stephens-Davidowitz, 2014) .
T142 22195-22493 Sentence denotes 18 In our case, we are interested in searches of the Spanish word for hand sanitizers: "gel" or "gel antibacterial." We downloaded the information in pairs of states keeping constant the state with the highest value of searches between 2008 and 2009 because Google Trends only releases it as index.
T143 22494-22586 Sentence denotes In that way, our data provide the 14 Multiple symptoms can be associated with the swine flu.
T144 22587-22793 Sentence denotes The top two symptoms associated with potential cases of the swine flu were cough (90 percent) and fever (86 percent), with diarrhea, nausea or votiming being present in 13 percent of the cases (SSA, 2011) .
T145 22794-22909 Sentence denotes 15 An alternative to laboratory-confirmed cases could be the use of the actual number of people infected with H1N1.
T146 22910-23121 Sentence denotes However, this number is unknown, as infections do not always create influenza-like symptoms and different approaches are used to compute estimates for the aggregate number of infections (Shrestha et al., 2011) .
T147 23122-23321 Sentence denotes 16 We also explored data on news coverage from a targeted search for H1N1related articles during the period 2006-2012 in LexisNexis that included 14 major newspapers with national coverage in Mexico.
T148 23322-23413 Sentence denotes However, there is no spatial variation in this variable and cannot be used in the analysis.
T149 23414-23594 Sentence denotes 17 Mathers et al. (2005) classify Mexico's mortality records as of the highest quality globally, with 100% coverage, extensive usage of ICD codes and with only 5% illdefined codes.
T150 23595-23677 Sentence denotes The United States has the same numbers except that it has 7% of ill-defined codes.
T151 23678-23719 Sentence denotes Germany's record for this measure is 14%.
T152 23720-23947 Sentence denotes 18 Google even has a site dedicated to predict the incidence of the seasonal flu based on the results from a paper published in Nature (Ginsberg et al., 2009 ). same base, where the highest (lowest) volume is set to 100 (zero).
T153 23948-24101 Sentence denotes 19 Note that the index is a measure of "relative popularity" and so it already takes into account the size of the search volume in each state and period.
T154 24102-24224 Sentence denotes Table 1 presents summary statistics of the key variables used in our analysis for periods 2006-2008, 2009, and 2010-2012 .
T155 24225-24341 Sentence denotes The last column of Table 1 shows the p-values of the difference in means between the pre-2009 and post-2009 periods.
T156 24342-24467 Sentence denotes Given that H1N1 did not exist prior to 2009, the total number of confirmed cases of H1N1 is only available from 2009 onwards.
T157 24468-24662 Sentence denotes Diarrhea-related hospitalizations for children under the age of 5 were lower in the post-2009, compared to the pre-2009 period, and the difference is statistically significant (p-value = 0.000).
T158 24663-24769 Sentence denotes On the other hand, federal expenditures in health were higher in post-2009 than pre-2008 (pvalue = 0.020).
T159 24770-24943 Sentence denotes Except for these two variables, the test of difference in means suggests there is no difference between the pre-2009 and post-2009 periods as captured by most key variables.
T160 24944-25230 Sentence denotes We exploit the temporal (the onset of the swine flu in 2009) and cross-sectional variation (by state) of the swine flu to examine its effect on diarrhea cases, that is, diseases that may be prevented with improved hygiene behavior that followed the onset of the H1N1 pandemic in Mexico.
T161 25231-25369 Sentence denotes Using a balanced panel at the state and year-level, our difference-in-difference identification strategy is formally presented in Eq. (1),
T162 25370-25527 Sentence denotes where y st is the number of hospital discharges with a primary diagnosis of intestinal infections (henceforth referred to as diarrhea) for state s in year t.
T163 25528-25733 Sentence denotes Variable H1N1 st represents the cross-sectional and temporal variation in the number of laboratory-confirmed swine flu cases reported in each of the states and year (with values equal to zero before 2009).
T164 25734-25827 Sentence denotes We also investigate other treatment and baseline periods, which are discussed in Section 4.3.
T165 25828-26046 Sentence denotes We use H1N1 counts rather than rates because we believe that part of the mechanism through which individuals' perceptions changed was rooted in the perceived magnitude of the problem as reported on news media channels.
T166 26047-26218 Sentence denotes The news media reported the total number of cases that had been confirmed at the national level as well as the states where the highest number of cases had been confirmed.
T167 26219-26309 Sentence denotes 20 Thus, ␤ is our parameter of interest as it captures the differencein-difference impact.
T168 26310-26518 Sentence denotes Robust standard errors clustered at 32 states with a correction with a correction for small clusters are used and are complemented with p-values computed using a wild bootstrap method (Cameron et al., 2008) .
T169 26519-26604 Sentence denotes Eq. (1) includes controls for year and state fixed effects ( t and s , respectively).
T170 26605-26876 Sentence denotes The year fixed effects allow us to control for nationwide trends in diarrheal diseases while the state fixed effects account for time-invariant unobserved characteristics during the period of analysis at the state level (e.g., culture, geography, institutional settings).
T171 26877-27201 Sentence denotes In our main specification, we compare the changes in diarrhea cases between 2008 and 2009 as we expect several state characteristics, including health infrastructure (e.g., stocks of hospitals and clinics), to remain constant over such a short period, thereby reducing the possibility of a bias in the parameter of interest.
T172 27202-27400 Sentence denotes Thus, if the H1N1 pandemic induced changes in hygiene behavior, we would expect to observe a larger decline in the incidence of diarrheal dis- eases in states where the swine flu was more prevalent.
T173 27401-27480 Sentence denotes In other words, we would expect ␤ to be negative and statistically significant.
T174 27481-27574 Sentence denotes In the next section, we show the results of estimating Eq. (1) with the data described above.
T175 27575-27710 Sentence denotes Table 2 presents the results from running the specification described in Eq. (1) for 2009 and 2008, with state and year fixed effects .
T176 27711-27957 Sentence denotes As shown in Panel A, column 1, our estimate for effect of the 2009 H1N1 on diarrhea cases for children under five is negative, −0.105, and statistically significant at the five percent level, marginally, using the wild-bootstrap p-values (0.060).
T177 27958-28116 Sentence denotes That is, there were fewer hospital discharges related to diarrhea in states with more swine flu cases, even after controlling for time and state fixedeffects.
T178 28117-28248 Sentence denotes This coefficient implies that for every 1000 cases of the swine flu, there were 105 fewer cases of diarrhea in children under five.
T179 28249-28526 Sentence denotes Given the average number of diarrhea-related hospitalizations for this group (1117 in the period 2008-2009), the estimated association indicates that for every 1000 cases of the swine flu we observe a 9.4 percent decline in diarrhea-related hospitalizations (-0.105*1000/1117).
T180 28527-28769 Sentence denotes That is, 3404 cases of H1N1 (or 4.9 percent of all confirmed cases) would have the same effect in the reduction of diarrhea (32 percent) as the estimated average effect from the costly interventions reviewed by Ejemot-Nwadiaro et al. (2008) .
T181 28770-28937 Sentence denotes This finding is reinforced when using the morbidity data (Panel B) that covers cases recorded in all public and private health centers, except for hospital inpatients.
T182 28938-29069 Sentence denotes We find that 1000 cases of the H1N1 are linked to a 3.5 percent reduction in diarrhea cases among young children (p-value = 0.051).
T183 29070-29257 Sentence denotes This impact is smaller than the 9.4 percent found in the inpatient setting, suggesting that the effect is more pronounced among severe cases, that is, those that required hospitalization.
T184 29258-29460 Sentence denotes In this section we examine the possibility that the documented reductions in diarrhea cases were purely "mechanical" and driven by a misclassification of diagnoses created by the onset of the swine flu.
T185 29461-29641 Sentence denotes For example, with the arrival of the H1N1, cases that should have been identified as diarrhea (belonging to ICD codes A00-A09X) could have been incorrectly classified as swine flu.
T186 29642-29763 Sentence denotes After all, up to 13 percent of the diarrhea swine flu cases exhibited vomit, nausea or diarrhea as an additional symptom.
T187 29764-29848 Sentence denotes We argue that this misclassification is an unlikely event for the following reasons.
T188 29849-29973 Sentence denotes First, as explained in the data section above, the H1N1 cases used in our study were confirmed cases using laboratory tests.
T189 29974-30145 Sentence denotes So even if some of them included a diarrhea symptom, these cases were coded as J09 in our data because a strain of the novel type of influenza was found in these patients.
T190 30146-30217 Sentence denotes Second, the recorded disease is made by a trained medical professional.
T191 30218-30410 Sentence denotes So if parents suspect their children have H1N1, when the actually have diarrhea, what is recorded is the actual assessment of the physician and not what the patient (or his parents) suspected.
T192 30411-30763 Sentence denotes 21 Third, we expect medical professionals to be less likely to misdiagnose a diarrhea case not only because of their medical training but because Mexico has identified intestinal infections as a public health issue based on the magnitude and prevalence of the disease (with at least 11% of children under five being affected by this problem each year).
T193 30764-30866 Sentence denotes These professionals are also more likely to be aware of the population at risk for different diseases.
T194 30867-31090 Sentence denotes As shown in Fig. 2 , which presents the age distribution of these two diseases for hospitalizations, 22 the H1N1 affected disproportionally school-going children and adults while diarrhea affects primarily children under 5.
T195 31091-31160 Sentence denotes This difference further reduces the possibility of misclassification.
T196 31161-31403 Sentence denotes Fourth, even if one assumes that doctors might not be fully aware of these epidemiological differences but rather have a flat prior with respect to the risk by age groups, then we should expect the misclassification to take place at all ages.
T197 31404-31613 Sentence denotes However, when we run our main specification for other age groups and not just for children under five, we do not find evidence suggesting there is a mechanical misclassification of diarrhea to H1N1 (Table 3 ).
T198 31614-31715 Sentence denotes The parameter for the H1N1 is negative and statistically significant for those under five (column 2).
T199 31716-31942 Sentence denotes However, it is positive, small and not statistically different from zero for all other age groups (columns 1, 3-5), including older patients who are the second most at-risk age group of diarrhea (as shown in Fig. 2, Panel B) .
T200 31943-32147 Sentence denotes This pattern −negative effect for children under five and positive but close to zero for all other groups-is found using the hospitalization (Panel A) data as well as the overall morbidity data (Panel B).
T201 32148-32235 Sentence denotes Moreover, we explore other outcomes that could be affected by better hygiene practices.
T202 32236-32463 Sentence denotes In Table 4 we include cases of conjunc-21 It is worth noticing that the official guidelines sent by the Mexican government to parents and schools rarely include diarrhea as one the key symptoms to identify a possible H1N1 case.
T203 32464-32559 Sentence denotes See SSA (2009b) (4) and (5) tivitis (ICD-10 codes B30 and H10) for children under 5 (column 2).
T204 32560-32647 Sentence denotes This outcome comes from the morbidity dataset obtained from the Anuarios de Morbilidad.
T205 32648-32717 Sentence denotes We find a negative association between H1N1 and conjunctivitis cases.
T206 32718-32810 Sentence denotes However, conjunctivitis affects only a fraction of children under five compared to diarrhea.
T207 32811-32926 Sentence denotes In 2008, for instance, there were 1.5 million cases of diarrhea nationwide but only 89,103 cases of conjunctivitis.
T208 32927-33001 Sentence denotes This could explain the lack of statistical significance for this estimate.
T209 33002-33259 Sentence denotes When we add hepatitis A (ICD-10 code B15, also from the Anuarios de Morbilidad) and conjunctivitis together as a new outcome we continue to observe a negative association with H1N1, alas unable to reject the null hypothesis (results available upon request).
T210 33260-33395 Sentence denotes Again, this could be explained by the few cases of hepatitis A among this age group (only 4348 in 2008) relative to the diarrhea cases.
T211 33396-33622 Sentence denotes We think this evidence, although not as strong as desired, adds to the support that the negative, robust and statistically significant effect of H1N1 on diarrhea is less likely to come from a mechanical classification problem.
T212 33623-33820 Sentence denotes Finally, we take advantage of the fact that diarrhea cases are classified in different ICD codes depending on the cause or disease etiology, where for most cases the cause of diarrhea is not known.
T213 33821-34157 Sentence denotes If during the H1N1 outbreak doctors misclassified diarrhea cases, these cases are more likely to come from those where the cause is unknown (ICD-10 code A09X) and much less so, if at all, from those where the cause is known (ICD-10 codes A00-A08) (see Appendix Table 2 in Supplementary material for details about specific ICD-10 codes).
T214 34158-34296 Sentence denotes In Table 4 we test for this hypothesis by using the ratio between known cases of diarrhea and the unknown sources as our outcome variable.
T215 34297-34464 Sentence denotes Misclassification implies that more cases of H1N1 will be positively associated with this ratio: the denominator (the unknown sources) decreases but not the numerator.
T216 34465-34532 Sentence denotes Our estimates strongly reject this prediction of misclassification.
T217 34533-34608 Sentence denotes We find no association between the ratio and the H1N1 (Table 4 , column 1).
T218 34609-34852 Sentence denotes Specifically, our point estimate using hospitalizations is 0.0001 (bootstrapped p-value = 0.853) and a similarly small and not statistically different from zero estimate when using the morbidity dataset (coefficient = 0.0001, p-value = 0.136).
T219 34853-35888 Sentence denotes 23 Taken together, for the period of analysis. a The dependent variable is annual hospital discharges as specified in each column. b Known causes include International Classification of Diseases (ICD-10) A00-A08; Unknown causes include ICD-10 code A09X. c Injuries include ICD-10 codes S00-S798. d Hip-related procedures include codes that capture fracture of femur (S72), arthrosis of hip (M16), complications of surgical and medical care (T80-T85), presence of orthopedic joint implants (Z96.6), fracture of bone following insertion of orthopedic implant (M96.6), and fitting and adjustment of orthopedic device (Z46.7). e H1N1 denotes the number of confirmed H1N1 cases in a given state during the treatment period (2009), and zero otherwise (2008). f p-value denotes the p-value of wild bootstrapped standard error to correct for small number (32) of clusters. g The dependent variable is the annual number of diarrhea cases or deaths due to diarrhea as specified in each column. h Conjunctivitis includes ICD-10 codes B30 and H10.
T220 35889-35992 Sentence denotes all these results indicate that our findings are not driven by some misclassification of the diagnosis.
T221 35993-35995 Sentence denotes 24
T222 35996-36089 Sentence denotes A key advantage of comparing diarrhea cases between 2009 and 2008 is their proximity in time.
T223 36090-36331 Sentence denotes In such a short period, the inclusion of state fixed effects serves as a more credible assumption because unobservables, such as culture or geography and maybe even institutions, are less likely to vary compared to the use of longer periods.
T224 36332-36583 Sentence denotes Nonetheless, it could be the case (however unlikely) that some of the unobserved characteristics specific to the 2008 cross-sectional distribution of the diarrhea cases could "predict" the spread of the 2009 swine flu and therefore bias our estimates.
T225 36584-36682 Sentence denotes With that in mind, we explore whether redefining or expanding the base period alters our findings.
T226 36683-36775 Sentence denotes We consider two alternative specifications using the hospitalization and morbidity outcomes.
T227 36776-36849 Sentence denotes First, following Eq. (1) we estimate two pairwise comparisons separately:
T228 36850-36928 Sentence denotes 2009 vs. 2007 (column 2 of Table 2 ) and 2009 vs. 2006 (column 3 of Table 2 ).
T229 36929-37235 Sentence denotes The second specification discards the pairwise comparison and expands the sample 24 We also explored the possibility that, before 2009, the new strain of the H1N1 virus might have been a latent disease and those cases were incorrectly labeled as diarrhea, because the new virus has not been identified yet.
T230 37236-37554 Sentence denotes Based on the number of H1N1 cases in 2009 for children under five (7238) and that 13% of cases, that at most, could include a diarrhea-like symptom, we estimated that the highest number of cases incorrectly labeled as diarrhea for 2008 cannot exceed 2.3 percent of the hospitalizations and 0.06% of the morbidity data.
T231 37555-37668 Sentence denotes Re-running our equation with those reductions applied to 2008 do not change our results (available upon request).
T232 37669-37714 Sentence denotes We thank an anonymous referee for this point.
T233 37715-37776 Sentence denotes to include all years 2006-2009 (columns 4 and 5 of Table 2 ).
T234 37777-37895 Sentence denotes The inclusion of more years permits us to add state-specific trends that were not possible in the pairwise comparison.
T235 37896-37998 Sentence denotes The results of these new specifications indicate that our findings are not sensitive to these changes.
T236 37999-38096 Sentence denotes Specifically, defining 2007 or 2006 as the base year does not qualitatively alter our conclusion.
T237 38097-38268 Sentence denotes We continue to find a negative association (but with lower precision) and these parameters are not statistically different from the estimates using the original base year.
T238 38269-38612 Sentence denotes Furthermore, expanding the data to include 2006 through 2009 we conclude that controlling for state trends (column 5) or not (column 4) provides robust findings: areas with a higher incidence of H1N1 see a larger decline in the number of diarrhea cases (with significant levels of 10 percent for hospitalizations and even lower for morbidity).
T239 38613-38710 Sentence denotes All these findings hold when using the hospitalization data (Panel A) or the morbidity (Panel B).
T240 38711-38932 Sentence denotes Thus, it is unlikely that our results are capturing pre-existing trends, as we continue to find a negative association between H1N1 and diarrhea cases after we control for time varying unobserved characteristics by state.
T241 38933-39011 Sentence denotes We further explore the issue of possible, though unlikely, preexisting trends.
T242 39012-39201 Sentence denotes In Fig. 3 Panel A we first show that states with a higher incidence of the 2009 swine flu had a larger decline in the number of diarrheal cases relative to the years preceding the outbreak.
T243 39202-39317 Sentence denotes We then examine the impact of the prevalence of the H1N1 pandemic on diarrhea cases for the periods preceding 2009.
T244 39318-39517 Sentence denotes Fig. 3 , Panel B, illustrates that there is no association between diarrhearelated cases between 2008 and 2007 (before the H1N1 outbreak) and the number of confirmed swine flu cases observed in 2009.
T245 39518-39586 Sentence denotes The regression analog to this figure is shown in Table 2 , column 6.
T246 39587-39841 Sentence denotes There we run the same specification as in Eq. (1) for the diarrhea outcomes in 2006-2007 and 2007-2008 but incorrectly assign the 2009 H1N1 distribution to these previous periods of time (for hospitalizations and morbidity, Panels A and B, respectively).
T247 39842-39895 Sentence denotes As before, we should find no effect of the 2009 H1N1.
T248 39896-40029 Sentence denotes Otherwise, this would be evidence in favor of unobserved variables predicting the 2009 cross-sectional distribution of the swine flu.
T249 40030-40150 Sentence denotes In each case, hospitalizations and morbidity data, the estimates for this falsification test indicate true zero effects.
T250 40151-40412 Sentence denotes These zero estimates and the lack of statistically significant effects provide a much stronger validation of our identification strategy and it is consistent with the visual evidence provided in Fig. 3 Panel B as well as the two maps presented before (Fig. 1) .
T251 40413-40536 Sentence denotes For our next set of falsification tests, we continue to compare data between 2008 and 2009 but alter the outcomes examined.
T252 40537-40954 Sentence denotes In particular we use: injuries caused by external factors 25 (e.g. traffic accidents, ICD-10 codes S00-T98), hip-related procedures (ICD-10 codes S72, M16, T80-T85, Z96.6, M96.6, and Z46.7), all hospital discharges (all ICD-10 codes excluding H1N1 cases) as well as mortality due to gastrointestinal problems (see Appendix Table 2 in Supplementary material for more details about the ICD-10 codes for these diseases).
T253 40955-41164 Sentence denotes First, as a way to start introducing some of the possible mechanisms behind the observed effect of the swine flu (i.e., hand washing) we show that the H1N1 does not affect discharges unrelated to hand washing.
T254 41165-41365 Sentence denotes Specifically, hospital discharges due to injuries serve as a valid placebo effect and we would expect to find statistically insignificant effects when we estimate Eq. (1) using injuries as an outcome.
T255 41366-41640 Sentence denotes This is precisely what we observe in col- 25 Injuries includes trauma to body, burns, poisoning due to external factors such as falls, traffic accidents, self-inflicted injuries, exposure to inanimate falling, thrown or projected objects, and aggressions. umn 3 of Table 4 .
T256 41641-41724 Sentence denotes The effects are again true zeroes: very small effects with smaller standard errors.
T257 41725-41905 Sentence denotes For example, the point estimate is 0.005 (SE = 0.007, bootstrapped p-value = 0.782), which is twenty times smaller than the corresponding estimate for diarrhea (in absolute value).
T258 41906-42182 Sentence denotes Second, we want to rule out the possibility that we are attributing our main findings to changes in healthcare-seeking behavior, namely, that there were fewer people going to the hospital in areas with higher prevalence of H1N1 in order to avoid contact with sick individuals.
T259 42183-42332 Sentence denotes We provided evidence against this possibility earlier as we showed that the effects are also observed among morbidity cases, beyond hospitalizations.
T260 42333-42499 Sentence denotes We explore this using hospital discharges associated with hip-related procedures for all age groups, and hospital discharges (excluding H1N1) for children under five.
T261 42500-42576 Sentence denotes Hip-related procedures try to capture hospital visits that could be delayed.
T262 42577-42693 Sentence denotes If these procedures were negatively related to the H1N1, we would find evidence that adults were avoiding hospitals.
T263 42694-42743 Sentence denotes In column 3 of Table 4 we identify a null result.
T264 42744-42928 Sentence denotes Similarly, if we observe a statistically significant decline in all types of hospitalizations for children, it would also suggest that parents were not taking their children hospitals.
T265 42929-42997 Sentence denotes A null result for this outcome is presented in column 4 of Table 4 .
T266 42998-43105 Sentence denotes If anything, in both cases we find a (very small) positive parameter that is not statistically significant.
T267 43106-43228 Sentence denotes Thus, we can rule out the possibility that our findings come from people avoiding hospitals during the swine flu pandemic.
T268 43229-43355 Sentence denotes 26 In column 3 of Table 4 Panel B, we show the results of the analysis where mortality due to diarrhea is the outcome measure.
T269 43356-43548 Sentence denotes The estimated coefficient is 0.0003 and is not statistically significant, implying that there is no change in overall child mortality due to diarrhea in areas with more cases of the swine flu.
T270 43549-43686 Sentence denotes This is important as we can rule out deaths from diarrhea happening at home, rather than at hospitals, for areas of high H1N1 prevalence.
T271 43687-43689 Sentence denotes 27
T272 43690-43734 Sentence denotes How did the swine flu reduce diarrhea cases?
T273 43735-44031 Sentence denotes In the previous section we have already suggested one possible explanation: the swine flu created a change in hygiene practices that led to more hand washing with soap (or use of antibacterial gels) and this led to fewer diarrhea cases requiring hospitalization, as well as fewer morbidity cases.
T274 44032-44140 Sentence denotes In this section we provide further evidence in favor of this mechanism and rule out other possible pathways.
T275 44141-44143 Sentence denotes 28
T276 44144-44249 Sentence denotes In this subsection, we examine several avenues that could explain the mechanisms underlying our findings.
T277 44250-44299 Sentence denotes First, we consider "business-as-usual" variables.
T278 44300-44520 Sentence denotes These include, state as well as federal health expenditures, the distribution of oral rehydration salts, the total number of vaccines administered and changes in health infrastructure measured by number of hospital beds.
T279 44521-44723 Sentence denotes In Table 5 we display the results of using our difference-in-difference approach described in Eq. (1) when these variables are considered as outcomes, after controlling for time and state fixed effects.
T280 44724-44935 Sentence denotes In columns 1 and 2, we show that the estimated coefficients for state and federal expenditures, respectively, are positive, very small and clearly not statistically significant based on the bootstrapped p-value.
T281 44936-45036 Sentence denotes Similar null results are found for oral rehydration salts, vaccines and hospital beds (columns 3-5).
T282 45037-45180 Sentence denotes The spread of the H1N1 is not related to these variables ruling them out as possible mechanisms to explain the improvements in health outcomes.
T283 45181-45291 Sentence denotes We now present evidence in favor of a pathway where the 2009 H1N1 pandemic changed health behaviors in Mexico.
T284 45292-45370 Sentence denotes We start by exploring production and consumption patterns of hygiene products.
T285 45371-45587 Sentence denotes Mexican manufacturing data indicate that between 2008 and 2009, there was a 6.4 percentage point increase in production of soaps, cleaners and cosmetics; compared to a 2.3 percentage point increase from 2003 to 2007.
T286 45588-45752 Sentence denotes 29 In addition to the changes in production of soaps there is other evidence that suggests changes in hand washing behavior might have occurred during the pandemic.
T287 45753-46033 Sentence denotes A survey conducted in Mexico City and two states with varying prevalence of the swine flu showed that the top three mitigation efforts adopted to protect against the H1N1 virus included frequent washing of hands with soap, use of a mask, and hand sanitizer (Aburto et al., 2010) .
T288 46034-46111 Sentence denotes 30 We reproduce these findings in Appendix Table 5 in Supplementary material.
T289 46112-46243 Sentence denotes This table also shows that people in states 27 We also conducted additional tests to examine alternative functional specifications.
T290 46244-46421 Sentence denotes These analyses suggest that the linear specification with counts appears to be the preferred specification for our paper (see Appendix Tables 3 and 4 in Supplementary material).
T291 46422-46681 Sentence denotes 28 Recent papers on infectious diseases are exploring the role of viral interference; a process where individuals infected with the swine flu could become immune to other viruses (e.g., Gröndahl et al., 2014; Ånestad and Nordbø 2011; Casalegno et al., 2010) .
T292 46682-46740 Sentence denotes See also Wrammert et al. (2011) for related possibilities.
T293 46741-46869 Sentence denotes Whether the H1N1 served as an "antibody" for the viruses causing diarrhea (e.g., rotavirus) goes beyond the scope of this paper.
T294 46870-46959 Sentence denotes 29 These numbers underestimated purchases as imports of hand sanitizers are not included.
T295 46960-47021 Sentence denotes Furthermore, these data are not available at the state level.
T296 47022-47230 Sentence denotes 30 Although we are uncertain about the methodology, others have indicated that a survey conducted by Nielsen showed that the top two adopted measures by consumers in Mexico during the swine flu outbreak were:
T297 47231-47316 Sentence denotes 1) the use of face masks, and 2) hand washing with soap and water or hand sanitizers.
T298 47317-47646 Sentence denotes Nielsen also reported an increase in sales of soaps and hand sanitizers. http://economia.terra.cl/noticias/ noticia.aspx?idNoticia=200906171913 TRM 78156849, accessed on November 24, 2013, and www.cnnexpansion.com/get content.php?q = print&url = mi-dinero/ 2009/06/17/autoservicios-ganan-con-la-influenza, accessed June 11, 2013.
T299 47647-47747 Sentence denotes with higher incidence of the swine flu at the time of the survey had higher usage of hand sanitizer.
T300 47748-47978 Sentence denotes This supports our hypothesis that the H1N1 pandemic changed hygiene practices, leading to more hand washing with soap or at least more use of hand sanitizers, and this change led to a reduction in hospitalizations due to diarrhea.
T301 47979-48166 Sentence denotes 31 We complement these results by showing that Mexicans became more aware of the need to have better hygiene practices and increased their demand for knowledge about preventive behaviors.
T302 48167-48325 Sentence denotes Fig. 4 , Panels A and B, show the trend of public interest for hand sanitizers between 2007 through 2011 using data from Google searches originated in Mexico.
T303 48326-48560 Sentence denotes To understand the y-axis of Fig. 4 , it is important to note that Google Trends does not release the actual number of searches but instead provides an index, which Google describes it as a measure of "relative popularity" of searches.
T304 48561-48645 Sentence denotes As mentioned in the data section, the data represent an index ranging from 0 to 100.
T1 48646-48720 Sentence denotes In Fig. 4 , Panel A, we show the weekly index of searches throughout 2009.
T2 48721-48742 Sentence denotes The pattern is clear.
T3 48743-48871 Sentence denotes Prior to week 15 (early April) there are few searches for the expression "hand sanitizer" (gel or gel antibacterial in Spanish).
T4 48872-49044 Sentence denotes However, at the beginning of the swine flu outbreak in early April we observe a spike in the number of searches of more than five times relative to first weeks of the year.
T5 49045-49134 Sentence denotes The post-outbreak trend remained at a level that was higher than the pre-outbreak period.
T6 49135-49298 Sentence denotes We further expand this analysis in Panel B of Fig. 4 32 We test whether this demand for knowledge is a possible mechanism by including it as an outcome in Eq. (1).
T7 49299-49378 Sentence denotes We do this by constructing a panel dataset from searches by the state and year.
T8 49379-49503 Sentence denotes In columns 6 and 7 of Table 5 , we find a positive and large relationship between the incidence of H1N1 and Google searches.
T9 49504-49745 Sentence denotes The results of column 6 indicate that 1000 cases of the H1N1 are associated with an increase of 3.2 units in Google searches for hand sanitizers and it is statistically different from zero at the 10% level using bootstrapped standard errors.
T10 49746-49872 Sentence denotes This represents a substantial increase (42 percent) with respect to average value during the period of analysis (mean = 7.63).
T11 49873-50123 Sentence denotes Note that due to low search volume there are no data for eight states, 33 so in column 7 we ran our regression for Google searches replacing the missing values with zeroes (the lowest possible value in the Google Trends index) for those eight states.
T12 50124-50174 Sentence denotes This way, we are able to utilize the full dataset.
T13 50175-50491 Sentence denotes This imputation leads to similar findings −more Google searches in areas with a higher incidence of the H1N1-and it allows us to gain precision for the estimates by "recovering" those missing values (p-value 31 Similar behavioral changes were reported during an outbreak of Severe Acute Respiratory Syndrome or SARS.
T14 50492-50528 Sentence denotes See Leung et al. (2004) for details.
T15 50529-50684 Sentence denotes Also, there was a spike of purchases for hand sanitizers in the United States during the swine flu in 2009 (see Appendix Fig. 3 in Supplementary material).
T16 50685-50892 Sentence denotes Furthermore, some research indicates that the H1N1 pandemic led to an increase in hand washing behavior in the US (e.g., Jones and Salathe 2009; Rubin et al., 2009 ) making our mechanism even more plausible.
T17 50893-51107 Sentence denotes 32 Similar patterns −a spike around week 19 and higher searches relative to the pre-outbreak period-can be observed for Google searches of the word "cubrebocas" or face masks (not shown but available upon request).
T18 51108-51306 Sentence denotes Also, when dividing the sample of states by high and low levels of H1N1, we find that the spike happens in both types of states at around the same time (figure not shown but available upon request).
T19 51307-51543 Sentence denotes 33 These states are, in alphabetical order, Baja California Sur, Campeche, Colima, Chihuahua, Durango, Nayarit, Tlaxcala, and Zacatecas. (6) and (7) captures the intensity of search volume per state and year, which ranges from 0 to 100.
T20 51544-51624 Sentence denotes The dependent variable in columns (1)-(5) is the log of the outcome of interest.
T21 51625-52027 Sentence denotes Columns (1) and (2) denote the log of millions of expenditures in Mexican pesos. b p-value denotes the p-value of wild bootstrapped standard errors for each specification to correct for small number (32) of clusters. c In columns (6) the specifications exclude the states of Baja California Sur, Campeche, Colima, Chihuahua, Durango, Nayarit, Tlaxcala, and Zacatecas for which Google data were missing.
T22 52028-52118 Sentence denotes In column (7) we assigned a value of zero to states with missing Google searches. < 0.10).
T23 52119-52287 Sentence denotes These analyses indicate that the main mechanism arises from the demand for knowledge regarding hygiene practices and not so much from the other channels examined above.
T24 52288-52480 Sentence denotes Our key hypothesis is that the 2009 H1N1 shocked or nudged people into changing their behavior (washing their hands) and this behavioral change led to a decline in diarrhea cases for children.
T25 52481-52584 Sentence denotes Is this effect also observed with the spread of respiratory infections arising due to the seasonal flu?
T26 52585-52739 Sentence denotes Theoretical models predict that engagements in preventive behavior are triggered only when the (contagious) disease crosses a threshold (Philipson 2000) .
T27 52740-52851 Sentence denotes Such models would predict a null effect from the seasonal flu but an important reaction from the H1N1 pandemic.
T28 52852-52904 Sentence denotes To study this question we modify Eq. (1) as follows,
T29 52905-53020 Sentence denotes where y st represents the hospital discharges of diarrhea for children under five in state s and year t (A00-A09X).
T30 53021-53027 Sentence denotes In Eq.
T31 53028-53138 Sentence denotes (2) we are interested in the effect of the seasonal flu (Flu st ) for all ages (similar to our H1N1 variable).
T32 53139-53242 Sentence denotes We obtained these data from Mexico's SINAVE for years prior to the H1N1 pandemic (2006) (2007) (2008) .
T33 53243-53304 Sentence denotes This variable represents morbidity cases of the seasonal flu.
T34 53305-53483 Sentence denotes While both the swine and the seasonal flu could be considered as health shocks, the latter did not exhibit the unexpected magnitude and the uncertain nature of the H1N1 pandemic.
T35 53484-53634 Sentence denotes Thus we can test whether small, expected health shocks (the seasonal flu) have similar effects to larger and unexpected health shocks (the swine flu).
T36 53635-53757 Sentence denotes Analogous to Eq. (2), is the parameter of interest and as before, we control for state ( s ) and time ( t ) fixed effects.
T37 53758-53803 Sentence denotes We also include state-specific trends ( st ).
T38 53804-53882 Sentence denotes The results of estimating this equation are presented in column 7 of Table 2 .
T39 53883-53970 Sentence denotes Unlike the H1N1, there is no link between cases of the seasonal flu and diarrhea cases.
T40 53971-54115 Sentence denotes Each case of the seasonal flu is associated with 0.003 additional cases of diarrhea but this parameter is not statistically different from zero.
T41 54116-54205 Sentence denotes The spread of the seasonal flu does not have an effect on diarrhea as the 2009 H1N1 does.
T42 54206-54303 Sentence denotes This evidence suggests that small and expected health shocks like the seasonal flu do not matter.
T43 54304-54363 Sentence denotes Large and unexpected shocks like the 2009 H1N1 pandemic do.
T44 54364-54446 Sentence denotes This evidence is consistent with theoretical models reviewed by Philipson (2000) .
T45 54447-54549 Sentence denotes An important contribution of our paper is its capacity to test whether the effects continue over time.
T46 54550-54733 Sentence denotes In the previous sections we have shown that the onset of swine flu in 2009 is associated with a reduction in diarrheal diseases as measured by hospital discharges and morbidity cases.
T47 54734-54929 Sentence denotes We have presented robust evidence in favor of the causal nature of these effects, thereby ruling out pre-trends affecting both H1N1 and diarrhea cases and other possible alternative explanations.
T48 54930-55229 Sentence denotes While other interventions have been able to show the contemporaneous effect of information campaigns on reduction in diarrhea cases (see for examples the 14 papers reviewed by Ejemot-Nwadiaro et al. (2008) the evidence of whether those reductions would be sustained after the campaign ends is scant.
T49 55230-55484 Sentence denotes 34 While there are papers examining the persistence of the effects of hand washing campaigns (e.g., Cairncross et al., 2005; Wilson and Chandler, 1993) they concentrate mainly on hand washing practices rather than measuring possible declines in diarrhea.
T50 55485-55614 Sentence denotes Our paper represents a significant advantage as we directly test whether the 2009 pandemic led to sustained declines in diarrhea.
T51 55615-55744 Sentence denotes To address this issue we add more years to the control and treatment period so that our analysis includes data from 2006 to 2012.
T52 55745-55956 Sentence denotes By including the years after 2009, we can test whether the subsequent years had a similar impact as 2009, and also whether the effects remain the same when there are fewer cases and concerns about the swine flu.
T53 55957-56077 Sentence denotes We note that in 2009 there were over 70,000 confirmed cases of H1N1, but these numbers plummeted in the following years.
T54 56078-56165 Sentence denotes In 2010, there were 2698 swine flu cases followed by only 372 in 2011 and 4507 in 2012.
T55 56166-56326 Sentence denotes If the 2009 pandemic served as a "natural nudge" then the post-2009 H1N1 cases could be thought as "reminders" following the literature of behavioral economics.
T56 56327-56499 Sentence denotes As reviewed by Luoto and Carman (2014) , reminders have been used in several settings where agents need follow-up nudges to sustain their health-related behavioral changes.
T57 56500-56707 Sentence denotes In column 1 of Table 6 , our variable of interest captures the crosssectional and time series variation in H1N1 cases between 2009 and 2012 and as before, zero for all states and years between 2006 and 2008.
T58 56708-56812 Sentence denotes In other words, we replicate Eq. (1) but with more years for both the control and the treatment periods.
T59 56813-56921 Sentence denotes The coefficient of interest is −0.046, which is smaller than the coefficient of −0.105 in the main analysis.
T60 56922-57022 Sentence denotes This suggests that post-2009 H1N1 cases have, on average, a smaller impact compared to the original.
T61 57023-57151 Sentence denotes We then alter Eq. (1) slightly to estimate the persistence of the 2009 effect, controlling for the contemporaneous effect of the
T62 57153-57221 Sentence denotes The results of estimating Eq. (3) are shown in column 2 of Table 6 .
T63 57222-57387 Sentence denotes We find evidence of a persistence effect: an increase in cases of the 2009 H1N1 is associated with a decline in the number of diarrhea cases for children under five.
T64 57388-57537 Sentence denotes For every case of the 2009 H1N1 we observe 0.221 fewer cases of diarrhea, even after controlling for contemporaneous cases of H1N1 (p-value = 0.024).
T65 57538-57682 Sentence denotes Furthermore, note that the contemporaneous effect of H1N1 is now positive (but not statistically significant based on the bootstrapped p-value).
T66 57683-57849 Sentence denotes This positive sign is not surprising in the absence of behavioral change since 13 percent of the swine flu cases were associated with diarrhea as one of the symptoms.
T67 57850-57979 Sentence denotes This reinforces our hypothesis that it is the actual health shock of the 2009 H1N1 pandemic that triggered the behavioral change.
T68 57980-58161 Sentence denotes Next, we consider an event study by replacing the H1N1 variable in Eq. (3) with four interaction terms of this variable with binary indicators for each year in the period 2009-2012.
T69 58162-58240 Sentence denotes This allows us to evaluate the contemporaneous impact of each year separately.
T70 58241-58436 Sentence denotes Likewise, if the contemporaneous effect exists only in 2009 and disappears with future H1N1 cases this would be evidence of a nudge: people adjusted their behavior in the presence of a new shock.
T71 58437-58566 Sentence denotes The shock allowed them to reach an equilibrium behavior in the sense that future shocks no longer change their hygiene practices.
T72 58567-58675 Sentence denotes Now consider a situation where the first nudge changed behavior, but it did not lead to an optimal solution.
T73 58676-58823 Sentence denotes In this case, there is still "room for improvement" and further "reminders" are needed to foster improvements in the production of health outcomes.
T74 58824-59023 Sentence denotes In this case, it seems possible that further nudges could have larger, or smaller, effects than the first nudge depending on the degree of dynamic complementarities between nudges in periods 1 and 2.
T75 59024-59084 Sentence denotes 35 The results are presented in columns 3 and 4 of Table 6 .
T76 59085-59193 Sentence denotes Column 3 indicates that the effect is negative in both 2009 and 2010 but with larger effects for the latter.
T77 59194-59245 Sentence denotes The results, however, disappear with the 2012 H1N1.
T78 59246-59344 Sentence denotes These findings suggest that further reminders help reducing diarrhea cases but for a limited time.
T79 59345-59647 Sentence denotes Most importantly, in column 4, and analogous to column 2, when accounting for the persistence effect of the 2009 pandemic, we find that the contemporaneous effects become substantially less relevant −much smaller in magnitude and no longer statistically different from zero-but the 2009 effect remains.
T80 59648-59818 Sentence denotes These results suggest that as a health shock, the 2009 H1N1 pandemic had a contemporaneous and a long-lasting effect in the reduction of diarrhea cases of young children.
T81 59819-59999 Sentence denotes This paper shows that severe health shocks such as the H1N1 pandemic in Mexico led to a long-lasting improvement in health outcomes by reducing diarrhea cases among young children.
T82 60000-60160 Sentence denotes Several placebo and robustness checks validate our difference-indifference identification strategy and strengthen the interpretation of our estimates as causal.
T83 60161-60512 Sentence denotes While other mechanisms are possible, we present evidence supporting the hypothesis that the pandemic was a shock that induced changes in hygiene practices and motivated people living in areas with higher prevalence of the swine flu to acquire information about better hygiene practices and to wash their hands or increase their use of hand sanitizers.
T84 60513-60585 Sentence denotes These findings expand our knowledge of health economics in several ways.
T85 60586-60875 Sentence denotes First, as reviewed by Cawley and Ruhm (2012) , previous studies emphasizing the role of health behaviors as key inputs 35 When the H1N1 impacts become larger for all periods after 2009 an alternative explanation could come from structural changes in the health system or mass vaccinations.
T86 60876-60942 Sentence denotes However, we do not observe such pattern in the post-2009 analysis.
T87 60943-61034 Sentence denotes Furthermore, we have already ruled out vaccinations as a possible mechanism in section 5.1.
T88 61035-61234 Sentence denotes We thank an anonymous referee for this insight. in the production of health outcomes have focused on chronic rather than infectious diseases and on advanced economies instead of developing countries.
T89 61235-61456 Sentence denotes In that regard, by focusing on gastrointestinal infections in Mexico, our study expands our knowledge of the role of behavioral changes in a much less investigated setting and addresses an important gap in the literature.
T90 61457-61808 Sentence denotes Second, the fact that the 2009 pandemic matters for behavioral change, compared to the null effect found from the smaller (and more predictable) seasonal flu, provides empirical support for theoretical models where a decision to engage in preventive behavior is triggered only when the (contagious) disease crosses a threshold (e.g., Philipson 2000) .
T91 61809-62043 Sentence denotes Furthermore, our paper complements recent advances in behavioral economics by exploring how health shocks, such as pandemics, can act as "natural nudges" that affect the production of health outcomes and generate long-lasting effects.
T92 62044-62108 Sentence denotes Our findings raise several issues regarding policy implications.
T93 62109-62358 Sentence denotes First, we show that business-as-usual strategies, such as overall government health expenditures, vaccinations campaigns as well changes in infrastructure (e.g., hospital beds) are unlikely to be behind the reasons for the decline in diarrhea cases.
T94 62359-62547 Sentence denotes 36 During major health emergencies, such as pandemics, individuals increase their demand for knowledge about ways to remain healthy (e.g. learning about better hygiene practice increases).
T95 62548-62815 Sentence denotes If governments facilitate access to low cost information sources, such as search engines, (or hot lines, TV or radio spots), especially in areas where the disease is more prevalent, our results indicate that the public will use these resources to acquire information.
T96 62816-63069 Sentence denotes In that setting, health outbreaks or emergencies could have unanticipated positive effects as long as the population is willing to change behaviors under the appropriate environment, e.g., with adequate information, incentives, and social acceptability.
T97 63070-63186 Sentence denotes Furthermore, our results from Google searches indicate that agents seek information broadly by using search engines.
T98 63187-63297 Sentence denotes Thus, the information to help address their demand does not need to be provided exclusively by the government.
T99 63298-63387 Sentence denotes During these emergencies, profit-seeking firms could provide a public health service too.
T100 63388-63615 Sentence denotes This is consistent with the points made by Mathios (1990, 1995) indicating that when producers are allowed to reveal the advantages of their products, firms could provide key information to consumer who then react to this news.
T101 63616-63900 Sentence denotes For example, producers and sellers of hand sanitizers or other products that improve hygiene practices could complement government efforts by advertising the benefits of their products, especially when government's health budgets are small as in the case of many developing countries.
T102 63901-64189 Sentence denotes An open research question is whether market friendly policies, such as low entry costs, could complement government efforts during health emergencies by allowing more firms to enter the market and supply the demand for health products that consumers are seeking, as shown by our findings.
T103 64190-64377 Sentence denotes Finally, health shocks such as the swine flu, HIV or cancer must be considered "high-water marks" as indicated by Smith et al. (2001) regarding the effectiveness of information campaigns.
T104 64378-64641 Sentence denotes Therefore, the question remains whether it is indeed possible to design information messages that could alter and sustain health behaviors analogous to the effects of the H1N1 pandemic in Mexico, but without the obvious adverse consequences of a health emergency.
T105 64642-64827 Sentence denotes A possible way to identify these messages could be found in the marketing strategies implemented in another Latin America country, Uruguay, as part of a nationwide antismoking campaign.
T106 64828-65074 Sentence denotes Harris et al. (2015) find that the inclusion of warning messages in cigarette packages, showing explicit pictograms of newborns affected by smoking during pregnancy, led to a higher smoking cessation for the targeted population of pregnant women.
T107 65075-65246 Sentence denotes Future research, should explore whether an analogous system of effective messages could be applied to the context of promoting long-lasting and improved hygiene practices.