Acknowledgements
Members of the Cochrane COVID‐19 Diagnostic Test Accuracy Review Group include:
the project team (Deeks JJ, Dinnes J, Takwoingi Y, Davenport C, Leeflang MMG, Spijker R, Hooft L, Van den Bruel A, McInnes MDF, Emperador D, Dittrich S);
the systematic review teams for each review:
Molecular, antigen, and antibody tests (Adriano A, Beese S, Dretzke J, Ferrante di Ruffano L, Harris I, Price M, Taylor‐Phillips S)
Signs and symptoms (Stuyf T, Domen J, Horn S)
Routine laboratory markers (Yang B, Langendam M, Ochodo E, Guleid F, Holtman G, Verbakel J, Wang J, Stegeman I)
Imaging tests (Salameh JP, McGrath TA, van der Pol CB, Frank RA, Prager R, Hare SS, Dennie C, Jenniskens K, Korevaar DA, Cohen JF, van de Wijgert J, Damen JAAG, Wang J)
the wider team of systematic reviewers from University of Birmingham, UK who assisted with title and abstract screening across the entire suite of reviews for the diagnosis of COVID‐19 (Agarwal R, Baldwin S, Berhane S, Herd C, Kristunas C, Quinn L, Scholefield B).
We thank Dr Jane Cunningham (World Health Organization) for participation in technical discussions and comments on the manuscript.
We would like to acknowledge Joanne Merckx for her contribution to the data extraction of nine papers in the initial stages of this review. Due to conflict of interest, a decision was taken to have a systematic reviewer, Nicholas Henschke, independently check all data extracted by her before publication.
The editorial process for this review was managed by Cochrane's EMD Editorial Service in collaboration with Cochrane Infectious Diseases. We thank Helen Wakeford, Anne‐Marie Stephani and Deirdre Walshe for their comments and editorial management. We thank Robin Featherstone for comments on the search and Mike Brown and Paul Garner for sign‐off comments. We thank Denise Mitchell for her efforts in copy‐editing this review.
Thank you also to peer referees Trish Greenhalgh, Robert Walton, Chris Cates and Lynda Ware, consumer referee Jenny Negus, and methodological referees Gianni Virgili and Marta Roqué, for their insights.
The editorial base of Cochrane Infectious Diseases is funded by UK aid from the UK Government for the benefit of low‐ and middle‐income countries (project number 300342‐104). The views expressed do not necessarily reflect the UK Government’s official policies.
Jonathan Deeks is a UK National Institute for Health Research (NIHR) Senior Investigator Emeritus. Yemisi Takwoingi is supported by a NIHR Postdoctoral Fellowship. Jonathan Deeks, Jacqueline Dinnes, Yemisi Takwoingi, Clare Davenport and Malcolm Price are supported by the NIHR Birmingham Biomedical Research Centre. This paper presents independent research supported by the NIHR Birmingham Biomedical Research Centre at the University Hospitals Birmingham NHS Foundation Trust and the University of Birmingham. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

Appendices

Appendix 1. World Health Organization case definitions

Severe pneumonia
Adolescent or adult: fever or suspected respiratory infection, plus one of the following: respiratory rate > 30 breaths/minute; severe respiratory distress; or oxygen saturation (SpO2) ≤ 93% on room air. Child with cough or difficulty in breathing, plus at least one of the following: central cyanosis or SpO2 < 90%; severe respiratory distress (for example, grunting, very severe chest indrawing); signs of pneumonia with a general danger sign: inability to breastfeed or drink, lethargy or unconsciousness, or convulsions.
Other signs of pneumonia may be present: chest indrawing, fast breathing (in breaths/minute): aged < 2 months: ≥ 60; aged 2 to 11 months: ≥ 50; aged 1 to 5 years: ≥ 40. While the diagnosis is made on clinical grounds; chest imaging may identify or exclude some pulmonary complications.

Acute respiratory distress syndrome (ARDS)
Onset within one week of a known clinical insult or new or worsening respiratory symptoms.
Chest imaging (that is, X‐ray, computed tomography scan, or lung ultrasound): bilateral opacities, not fully explained by volume overload, lobar or lung collapse, or nodules.
Origin of pulmonary infiltrates: respiratory failure not fully explained by cardiac failure or fluid overload. Need objective assessment (for example, echocardiography) to exclude hydrostatic cause of infiltrates/oedema if no risk factor present.
Oxygenation impairment in adults:
mild acute respiratory distress syndrome (ARDS): 200 mmHg < ratio of arterial oxygen partial pressure/fractional inspired oxygen (PaO2/FiO2) ≤ 300 mmHg (with positive end‐expiratory pressure (PEEP) or continuous positive airway pressure (CPAP) ≥ 5 cmH2O, or non‐ventilated);
moderate ARDS: 100 mmHg < PaO2/FiO2 ≤ 200 mmHg (with PEEP ≥ 5 cmH2O, or non‐ventilated);
severe ARDS: PaO2/FiO2 ≤ 100 mmHg (with PEEP ≥ 5 cmH2O, or non‐ventilated);
when PaO2 is not available, SpO2/FiO2 ≤ 315 mmHg suggests ARDS (including in non‐ventilated patients).
Oxygenation impairment in children: note OI = Oxygenation Index and OSI = Oxygenation Index using SpO2. Use PaO2‐based metric when available. If PaO2 not available, wean FiO2 to maintain SpO2 ≤ 97% to calculate OSI or SpO2/FiO2 ratio:
bilevel (non‐invasive ventilation or CPAP) ≥ 5 cmH2O via full‐face mask: PaO2/FiO2 ≤ 300 mmHg or SpO2/FiO2 ≤ 264;
mild ARDS (invasively ventilated): 4 ≤ OI < 8 or 5 ≤ OSI < 7.5;
moderate ARDS (invasively ventilated): 8 ≤ OI < 16 or 7.5 ≤ OSI < 12.3;
severe ARDS (invasively ventilated): OI ≥ 16 or OSI ≥ 12.3.

Appendix 2. Cochrane COVID‐19 Study Register searches
Source   Strategy
ClinicalTrials.gov  COVID‐19a
WHO ICTRP  Health topic: 2019‐nCov / COVID‐19
PubMed  (("2019 nCoV"[tiab] OR 2019nCoV[tiab] OR "2019 novel coronavirus"[tiab] OR "COVID 19"[tiab] OR COVID19[tiab] OR "new coronavirus"[tiab] OR "novel coronavirus"[tiab] OR "novel corona virus"[tiab] OR "SARS CoV‐2"[tiab] OR (Wuhan[tiab] AND (coronavirus[tiab] OR "corona virus"[tiab])) OR "COVID‐19"[Supplementary Concept] OR "severe acute respiratory syndrome coronavirus 2"[Supplementary Concept]) NOT ("animals"[MeSH Terms] NOT "humans"[MeSH Terms])) NOT (editorial[pt] OR comment[pt] OR letter[pt] OR newspaper article[pt])
aAutomatic term mapping links results for 2019‐nCoV, 2019 novel coronavirus, SARS‐CoV‐2, severe acute respiratory syndrome coronavirus 2.

Appendix 3. Living search from the University of Bern
We took the following information from the university of Bern website (see: ispmbern.github.io/covid-19/living-review/collectingdata.html).
The register is updated daily and CSV file downloads are made available.

1 April 2020
From 1 April 2020, we will retriev the curated BioRxiv/MedRxiv dataset (connect.medrxiv.org/relate/content/181).

26 to 31 March 2020
MEDLINE: (\"Wuhan coronavirus\" [Supplementary Concept] OR \"COVID‐19\" OR \"2019 ncov\"[tiab] OR ((\"novel coronavirus\"[tiab] OR \"new coronavirus\"[tiab]) AND (wuhan[tiab] OR 2019[tiab])) OR 2019‐nCoV[All Fields] OR (wuhan[tiab] AND coronavirus[tiab])))))
Embase: (nCoV or 2019‐nCoV or ((new or novel or wuhan) adj3 coronavirus) or covid19 or covid‐19 or SARS‐CoV‐2).mp.
BioRxiv/MedRxiv: ncov or corona or wuhan or COVID or SARS‐CoV‐2
With the kind support of the Public Health & Primary Care Library PHC (www.unibe.ch/university/services/university_library/faculty_libraries/medicine/public_health_amp_primary_care_library_phc/index_eng.html), and following guidance of the Medical Library Association (www.mlanet.org/p/cm/ld/fid=1713).

1 January 2020 to 25 March 2020
MEDLINE: ("Wuhan coronavirus" [Supplementary Concept] OR "COVID‐19" OR "2019 ncov"[tiab] OR (("novel coronavirus"[tiab] OR "new coronavirus"[tiab]) AND (wuhan[tiab] OR 2019[tiab])) OR 2019‐nCoV[All Fields] OR (wuhan[tiab] AND coronavirus[tiab])))))
Embase: ncov OR (wuhan AND corona) OR COVID
BioRxiv/MedRxiv: ncov or corona or wuhan or COVID

Appendix 4. CDC Library, COVID‐19 Research Articles Downloadable Database
Embase records from the Stephen B. Thacker CDC Library, COVID‐19 Research Articles Downloadable Database.
Records were obtained by the CDC library by searching Embase through Ovid using the following search strategy.
Source   Strategy
Embase  (coronavir* OR corona virus* OR betacoronavir* OR covid19 OR covid 19 OR nCoV OR novel CoV OR CoV 2 OR CoV2 OR sarscov2 OR 2019nCoV OR wuhan virus*).mp. OR ((wuhan OR hubei OR huanan) AND (severe acute respiratory OR pneumonia*) AND outbreak*).mp. OR Coronavirus infection/ OR coronavirinae/ OR exp betacoronavirus/Limits: 2020‐OR(novel coronavir* OR novel corona virus* OR covid19 OR covid 19 OR nCoV OR novel CoV OR CoV 2 OR CoV2 OR sarscov2 OR 2019nCoV OR wuhan virus*).mp. OR ((wuhan OR hubei OR huanan) AND (severe acute respiratory OR pneumonia*) AND outbreak*).mp. OR ((wuhan OR hubei OR huanan) AND (coronavir* OR betacoronavir*)).mp.Limits: 2019‐

Data
Presented below are all the data for all of the tests entered into the review.
Tests  Data tables by test
Test  No. of studies  No. of participants
1 Cough  8  2607
2 Sputum production  6  2467
3 Dyspnoea  7  2554
4 Hypoxia  1  2929
5 Haemoptysis  1  116
6 Positive auscultation findings  1  788
7 Respiratory symptoms (not specified))  1  788
8 Sore throat  6  2438
9 Nasal symptoms  5  2405
10 Loss of smell (anosmia) or loss of taste (ageusia)  1  870
11 Fever  9  5484
12 Low body temperature  1  3384
13 Shivers  1  132
14 Chills  2  1443
15 Myalgia or arthralgia  4  339
16 Myalgia or fatigue  2  1427
17 Fatigue  3  273
18 Headache  5  1700
19 Nausea/vomiting  3  489
20 Diarrhoea  6  1733
21 Abdominal pain  2  185
22 Gastrointestinal symptoms (not specified)  1  788
23 Low systolic blood pressure  1  3341
24 High systolic blood pressure  1  3341
25 Tachycardia  1  3373
26 Palpitations  1  132
27 Cough (non‐cross‐sectional study)  3  432
28 Sore throat (non‐cross‐sectional study)  3  432
29 Rhinorrhoea (non‐cross‐sectional study)  1  136
30 Nasal obstruction (non‐cross‐sectional study)  2  398
31 Loss of smell (anosmia) (non‐cross‐sectional study)  1  262
32 Loss of taste (ageusia) (non‐cross‐sectional study)  1  262
33 Positive auscultation findings (non‐cross‐sectional study)  1  34
34 Dyspnoea (non‐cross‐sectional study)  1  262
35 Chest tightness (non‐cross‐sectional study)  1  34
36 Fever (non‐cross‐sectional study)  2  296
37 Fatigue (non‐cross‐sectional study)  3  432
38 Myalgia or arthralgia (non‐cross‐sectional study)  1  262
39 Headache (non‐cross‐sectional study)  2  296
40 Diarrhoea (non‐cross‐sectional study)  3  812
41 Nausea/vomiting (non‐cross‐sectional study)  2  778
42 Gastrointestinal symptoms, not specified (non‐cross‐sectional study)  1  516
1  Test
Cough
2  Test
Sputum production
3  Test
Dyspnoea
4  Test
Hypoxia
5  Test
Haemoptysis
6  Test
Positive auscultation findings
7  Test
Respiratory symptoms (not specified))
8  Test
Sore throat
9  Test
Nasal symptoms
10  Test
Loss of smell (anosmia) or loss of taste (ageusia)
11  Test
Fever
12  Test
Low body temperature
13  Test
Shivers
14  Test
Chills
15  Test
Myalgia or arthralgia
16  Test
Myalgia or fatigue
17  Test
Fatigue
18  Test
Headache
19  Test
Nausea/vomiting
20  Test
Diarrhoea
21  Test
Abdominal pain
22  Test
Gastrointestinal symptoms (not specified)
23  Test
Low systolic blood pressure
24  Test
High systolic blood pressure
25  Test
Tachycardia
26  Test
Palpitations
27  Test
Cough (non‐cross‐sectional study)
28  Test
Sore throat (non‐cross‐sectional study)
29  Test
Rhinorrhoea (non‐cross‐sectional study)
30  Test
Nasal obstruction (non‐cross‐sectional study)
31  Test
Loss of smell (anosmia) (non‐cross‐sectional study)
32  Test
Loss of taste (ageusia) (non‐cross‐sectional study)
33  Test
Positive auscultation findings (non‐cross‐sectional study)
34  Test
Dyspnoea (non‐cross‐sectional study)
35  Test
Chest tightness (non‐cross‐sectional study)
36  Test
Fever (non‐cross‐sectional study)
37  Test
Fatigue (non‐cross‐sectional study)
38  Test
Myalgia or arthralgia (non‐cross‐sectional study)
39  Test
Headache (non‐cross‐sectional study)
40  Test
Diarrhoea (non‐cross‐sectional study)
41  Test
Nausea/vomiting (non‐cross‐sectional study)
42  Test
Gastrointestinal symptoms, not specified (non‐cross‐sectional study)

Characteristics of studies

Characteristics of included studies [ordered by study ID]
Ai 2020a
Study characteristics
Patient Sampling  Purpose: diagnosis of SARS‐CoV‐2 pneumoniaDesign: cross‐sectional multicentre prospective studyRecruitment: hospitalised pneumonia patientsSample size: n = 53 (20 cases)Inclusion criteria: suspected SARS‐COV‐2 pneumonia patients, defined as having pneumonia after chest CT (with 1 of the 2 following criteria met: fever or respiratory symptoms, normal or decreased WBC counts/decreasedExclusion criteria: not defined
Patient characteristics and setting  Facility cases: confirmed case: a positive SARS‐COV‐2 nucleotides result either by metagenomic sequencing or RT‐PCR assay for nasopharyngeal swab specimensFacility controls: pneumonia patients confirmed not to be infected by SARS‐Cov2 (2 PCR tests, 2 days in between)Country: ChinaDates: 22 January 2020‐19 February 2020Symptoms and severity: suspected SARS‐COV‐2 pneumonia (NCP): having pneumonia after chest CT with 1 of the 2 following criteria met: fever or respiratory symptoms, normal or decreased WBC counts/decreased lymphocyte counts, and a travel history or contact with patients with fever or respiratory symptoms from Hubei Province or confirmed cases within 2 weeksDemographics: median age cases 37 years, controls 39 years, gender distribution cases (M/F: 50/50), controls (M/F: 48.5/51.5)Exposure history: not specified
Index tests  Fever
Dry cough
Diarrhoea
Fatigue
Headache
Vomiting
Abdominal pain
Target condition and reference standard(s)  TC: COVID‐19 pneumonia
RS: a positive SARS‐COV‐2 nucleotides result either by metagenomic sequencing or RT‐PCR assay for nasopharyngeal swab specimens, repeated after 2 days if negative on day 0
Flow and timing  Time interval not specified. Reference standard at day 0 and day 2, index tests from electronic medical records but stated at pneumonia onset
Comparative   
Notes   
Methodological quality
Item   Authors' judgement   Risk of bias   Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?  Unclear      
Was a case‐control design avoided?  Yes      
Did the study avoid inappropriate exclusions?  Unclear      
Did the study avoid inappropriate inclusions?  No      
Could the selection of patients have introduced bias?     High risk   
Are there concerns that the included patients and setting do not match the review question?        High
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?  Unclear      
If a threshold was used, was it pre‐specified?  No      
Could the conduct or interpretation of the index test have introduced bias?     High risk   
Are there concerns that the index test, its conduct, or interpretation differ from the review question?        Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?  Yes      
Were the reference standard results interpreted without knowledge of the results of the index tests?  Unclear      
Could the reference standard, its conduct, or its interpretation have introduced bias?     Low risk   
Are there concerns that the target condition as defined by the reference standard does not match the question?        Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?  Unclear      
Did all patients receive the same reference standard?  Yes      
Were all patients included in the analysis?  Yes      
Could the patient flow have introduced bias?     Low risk   
Chen X 2020
Study characteristics
Patient Sampling  Purpose: diagnosis COVID‐19 pneumonia ‐ to identify differences in CT imaging and clinical manifestations between pneumonia patients with and without COVID‐19, and to develop and validate a diagnostic model for COVID‐19 based on radiological semantic and clinical featuresDesign: cross‐sectional multicentre retrospective studyRecruitment:
cases: consecutive patients with COVID‐19 admitted in 5 independent hospitals
controls: at the same period, another 66 consecutive pneumonia patients without COVID‐19 from Meizhou People’s HospitalSample size: n = 136 (cases = 70)Inclusion criteria: patients admitted with COVID‐19 pneumonia (cases) and patients admitted with non‐COVID‐19 pneumonia (controls)Exclusion criteria: not specified for cases except those from 1 hospital (Meizhou), for cases and controls in Meizhou: after chest CT neoplasm, tuberculosis, pulmonary oedema, pulmonary contusion, aspiration pneumonia, bronchitis, any local or systemic treatment before CT scan, normal CT image without epidemiological history
Patient characteristics and setting  Facility cases: pneumonia patients with positive SARS‐CoV‐2 testFacility controls: CT pneumonia patients with consecutive negative RT‐PCRCountry: ChinaDates: 1 January 2020‐8 February 2020Symptoms and severity: pneumonia patients for cases and control; unclear severity of casesDemographics: M/F: cases 41/29, controls 43/23
mean age: cases 42.9 range, 16‐69 years, controls 46.7 range, 0.3‐93 yearsExposure history: data about exposure to epidemic centres collected, but no results in the study nor in appendices
Index tests  Systolic BP
Diastolic BP
Respiration rate
Heart rate
Temperature
Dry cough
Fatigue
Sore throat
Stuffy
Runny nose
Target condition and reference standard(s)  TC: COVID‐19 pneumonia
RS: RT‐PCR and next generation sequencing for SARS‐Cov2
Flow and timing  Time interval not specified
Comparative   
Notes   
Methodological quality
Item   Authors' judgement   Risk of bias   Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?  Yes      
Was a case‐control design avoided?  Yes      
Did the study avoid inappropriate exclusions?  Yes      
Did the study avoid inappropriate inclusions?  No      
Could the selection of patients have introduced bias?     High risk   
Are there concerns that the included patients and setting do not match the review question?        High
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?  Unclear      
If a threshold was used, was it pre‐specified?  No      
Could the conduct or interpretation of the index test have introduced bias?     Unclear risk   
Are there concerns that the index test, its conduct, or interpretation differ from the review question?        Unclear
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?  Yes      
Were the reference standard results interpreted without knowledge of the results of the index tests?  Yes      
Could the reference standard, its conduct, or its interpretation have introduced bias?     Low risk   
Are there concerns that the target condition as defined by the reference standard does not match the question?        Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?  Unclear      
Did all patients receive the same reference standard?  Yes      
Were all patients included in the analysis?  Yes      
Could the patient flow have introduced bias?     Low risk   
Cheng 2020a
Study characteristics
Patient Sampling  Purpose: to identify the clinical features and CT manifestations of COVID‐19 and compare them with those of pneumonia occurring in patients who do not have COVID‐19Design: cross‐sectional single‐centre retrospective studyRecruitment: pneumonia patients who presented at a fever observation department in ShanghaiSample size: n = 33 (11 cases)Inclusion criteria: patients with clinical and radiological features of pneumonia, and a normal or reduced total leukocyte count or total lymphocyte count, plus an epidemiologic history that included travel or a history of residence in Hubei province or other areas where continuous transmission of local cases occurred within 14 days before onset of symptoms, a history of contact with patients who had fever or respiratory symptoms and were from Hubei province or other areas with continuous transmission of local cases within 14 days before onset of the disease, or clustering or epidemiologic association with the new coronavirus infectionExclusion criteria: not defined
Patient characteristics and setting  Facility cases: confirmed case: positive RT‐PCR test result obtained by a throat swab. Test was repeated when the first test was negativeFacility controls: pneumonia patients confirmed not to be infected by SARS‐Cov2 (2 PCR tests)Country: ChinaDates: 19 January 2020‐6 February 2020Symptoms and severity: pneumonia was defined as patients with at least 1 clinical symptom (i.e. cough, sputum, fever, dyspnoea, or pleuritic chest pain), a finding of either coarse crackles on auscultation or elevated inflammatory biomarkers, and observation of a new pulmonary opacification on chest CTDemographics: median age +‐ SD cases 50.36 +‐ 15.5, controls 43.59 +‐ 16.02, gender distribution cases (M/F: 8/3), controls (M/F: 7/15)Exposure history: cases 8/11, controls 7/22 (in the last 14 days with patients with fever or respiratory symptoms or with known cases)
Index tests  Fever
Cough
Sputum
Shortness of breath
Muscle ache
Diarrhoea
Sore throat
Peak body temperature
Target condition and reference standard(s)  TC: COVID‐19 pneumonia
RS: RT‐PCR testing on throat swab specimens
Tests were repeated if the first test was negative
Flow and timing  Time interval not specified, reference test at day 0 (or later when the first test was negative), index tests were questionnaired at day 0 for the presence of symptoms in the past period of time
Comparative   
Notes   
Methodological quality
Item   Authors' judgement   Risk of bias   Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?  Unclear      
Was a case‐control design avoided?  Yes      
Did the study avoid inappropriate exclusions?  Unclear      
Did the study avoid inappropriate inclusions?  No      
Could the selection of patients have introduced bias?     High risk   
Are there concerns that the included patients and setting do not match the review question?        High
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?  Yes      
If a threshold was used, was it pre‐specified?  No      
Could the conduct or interpretation of the index test have introduced bias?     High risk   
Are there concerns that the index test, its conduct, or interpretation differ from the review question?        Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?  Yes      
Were the reference standard results interpreted without knowledge of the results of the index tests?  Unclear      
Could the reference standard, its conduct, or its interpretation have introduced bias?     Low risk   
Are there concerns that the target condition as defined by the reference standard does not match the question?        Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?  Unclear      
Did all patients receive the same reference standard?  Yes      
Were all patients included in the analysis?  Yes      
Could the patient flow have introduced bias?     Low risk   
Feng 2020a
Study characteristics
Patient Sampling  Purpose: diagnosis COVID‐19 pneumoniaDesign: cross‐sectional, retrospective, single‐centre studyRecruitment: patients admitted to ED with history of exposure to COVID‐19Sample size: n = 132 (cases = 7)inclusion criteria: all patients admitted to the fever clinic of the ED of the First medical center, Chinese People's Liberation Army General Hospital (PLAGH) in Beijing with the epidemiological history of exposure to COVID‐19 according to WHO interim guidanceExclusion criteria: < 14 years old, no other criteria specified
Patient characteristics and setting  Facility cases: among clinically suspected patients: those with a positive RT‐PCRFacility controls: clinically non‐suspected patients + suspected patients with negative RT‐PCRCountry: ChinaDates: 14 January 2020‐9 February 2020Symptoms and severity: all patients admitted, with exposure history to COVID‐19, so all levels of severity; days from illness onset until admission (median, IQR): 2.0 (1.0‐5.0); patient population with general mild disease and limited presence of comorbidities (range 0%‐2.3% (COPD))Demographics: age: controls median 40.0 years (IQR 32.5‐54.5), cases median 39.0 years (IQR 37.0‐41.5)M%/F%: cases 71.4/28.6, controls 63.2/36.8Exposure history: epidemiological history of exposure to COVID‐19 (as per WHO guidance)
Index tests  Heart rate
Diastolic BP
Systolic BP
Fever (former: median only on all and cases ‐ no control median given)
Highest temperature
Cough
Shortness of breath
Muscle ache
Headache
Sore throat
Rhinorrhoea
Diarrhoea
Nausea
Vomiting
Chills
Shiver
Expectoration
Abdominal pain
Fatigue
Palpitation
Target condition and reference standard(s)  TC: COVID‐19 pneumonia
RS: in‐house RT‐PCR (E‐gene) ‐ at 4 institutions
Flow and timing  Index test and RS both taken on admission
Comparative   
Notes   
Methodological quality
Item   Authors' judgement   Risk of bias   Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?  Yes      
Was a case‐control design avoided?  Yes      
Did the study avoid inappropriate exclusions?  Yes      
Did the study avoid inappropriate inclusions?  Yes      
Could the selection of patients have introduced bias?     Low risk   
Are there concerns that the included patients and setting do not match the review question?        Low concern
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?  Yes      
If a threshold was used, was it pre‐specified?  No      
Could the conduct or interpretation of the index test have introduced bias?     High risk   
Are there concerns that the index test, its conduct, or interpretation differ from the review question?        Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?  Yes      
Were the reference standard results interpreted without knowledge of the results of the index tests?  Unclear      
Could the reference standard, its conduct, or its interpretation have introduced bias?     High risk   
Are there concerns that the target condition as defined by the reference standard does not match the question?        Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?  Yes      
Did all patients receive the same reference standard?  No      
Were all patients included in the analysis?  Yes      
Could the patient flow have introduced bias?     High risk   
Liang 2020
Study characteristics
Patient Sampling  Purpose: to estimate the prevalence of COVID‐19 in pneumonias during this period and to find the unique features of COVID‐19 as compared to pneumonias caused by other agentsDesign: cross‐sectional, single‐centre, retrospective studyRecruitment: 342 cases of pneumonia were diagnosed in Fever Clinic in Peking University Third Hospital. From these patients, 88 were reviewed by panel discussion as possible or probable cases of COVID‐19, and received 2019‐nCoV detection by RT‐PCRSample size: n = 88 (21 cases)Inclusion criteria: patients visiting the Fever Clinic at Peking University Third Hospital. Based on epidemiological history, epidemiological evidence, fever and/or respiratory symptoms, chest radiological findings and WBC results, cases with possible or probable COVID‐19 were sent for panel discussion and then for 2019‐nCoV detection by RT‐PCRExclusion criteria: COVID‐19 unlikely by panel discussion; lack of CT scan or no signs of pneumonia on CT scan; paediatric patients
Patient characteristics and setting  Facility cases: 2019‐nCoV real‐time PCR testing, which was positive in 19 cases (confirmed cases). In another 2 patients, though PCR testing was negative, a clinical diagnosis was made according to
epidemiological evidence, consistent clinical and CT findings (clinical cases)Facility controls: for the cases with negative viral detection, the diagnosis of COVID‐19 was excluded based on inconsistent epidemiological, clinical or radiological dataCountry: ChinaDates: 21 January 2020‐15 February 2020SymptomsFever with a mean body temperature of 37.8 C
Cough
Expectoration
Fatigue
Headache
Dizziness
Shortness of breath
Myalgia or arthralgia
Sore throat
Nasal symptoms and diarrhoea
Severity of COVID‐19Mild‐moderate: fever and/or respiratory symptoms with pneumonia in radiology examination, without signs of severe or very severe diseases
Severe: presence of 1 of the following: respiratory rate ≥ 30 beat/min; SpO2 ≤ 93% at rest; PaO2/FiO2 ≤ 300 mmHg
Very severe: presence of 1 of the following: severe respiratory failure requiring mechanical ventilation; shock; complicated with other organ failure and requiring ICU admission
Demographics: COVID‐group only: median age was 42.0 years (25th‐75th percentile, 34.5‐66.0 years). Range 24‐85. Male/female: 11 (52.4%)/10 (47.6%)Exposure history: 19/21 (90.5%) had a clear epidemiological history of COVID‐19. 7 patients, from 5 family clusters, had close contact with their family members
Index tests  Fever with a mean body temperature of 37.8 C
Cough
Expectoration
Fatigue
Headache
Dizziness
Shortness of breath
Myalgia or arthralgia
Sore throat
Nasal symptoms and diarrhoea
Target condition and reference standard(s)  TC: COVID‐19 pneumonia
RS: 2019‐nCoV real‐time PCR testing or clinical diagnosis was made according to epidemiological evidence, consistent clinical and CT findings
Flow and timing  Time interval not specified
Comparative   
Notes   
Methodological quality
Item   Authors' judgement   Risk of bias   Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?  Unclear      
Was a case‐control design avoided?  Yes      
Did the study avoid inappropriate exclusions?  No      
Did the study avoid inappropriate inclusions?  No      
Could the selection of patients have introduced bias?     High risk   
Are there concerns that the included patients and setting do not match the review question?        High
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?  Yes      
If a threshold was used, was it pre‐specified?  No      
Could the conduct or interpretation of the index test have introduced bias?     High risk   
Are there concerns that the index test, its conduct, or interpretation differ from the review question?        Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?  Yes      
Were the reference standard results interpreted without knowledge of the results of the index tests?  No      
Could the reference standard, its conduct, or its interpretation have introduced bias?     Low risk   
Are there concerns that the target condition as defined by the reference standard does not match the question?        Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?  Unclear      
Did all patients receive the same reference standard?  Yes      
Were all patients included in the analysis?  Yes      
Could the patient flow have introduced bias?     High risk   
Nobel 2020
Study characteristics
Patient Sampling  Purpose: assess GI symptoms in COVID‐19 and their association with short‐term outcomesDesign: diagnostic case‐control, retrospective studyRecruitment: adults who underwent nasopharyngeal swab testing for SARS‐CoV‐2 at outpatient settings: clinics or the ED, of New York‐Presbyterian‐Columbia or the medical centre's affiliates in New YorkSample size: 516 (278 cases)Inclusion criteria: adults ≥ 18 years of age who underwent nasopharyngeal swab testing for SARS‐CoV‐2. Indications for testing during this period were respiratory symptoms (cough, fever, shortness of breath) with intent to hospitalise or the same symptoms in essential personnel.Exclusion criteria: if insufficient data were available in the electronic medical record or if testing was performed during a pre‐existing inpatient admission
Patient characteristics and setting  Facility cases: SARS‐CoV‐2 PCR test result positive (1 test)Facility controls: SARS‐CoV‐2 PCR test result negativeCountry: USADates: 10 March 2020‐21 March 2020Symptoms and severity: respiratory symptoms (cough, fever, shortness of breath) with intent to hospitalise or in essential workersDemographics: median age: 51‐70 years (cases and controls), gender distribution: cases (M/F(%): 52/48), controls (M/F(%): 45/55)Exposure history: not specified
Index tests  GI symptoms: diarrhoea, vomiting/nausea
Target condition and reference standard(s)  TC: SARS‐Cov‐2 infection
RS: SARS‐CoV‐2 PCR test, once (nasopharyngeal swab)
Flow and timing  Time interval: both taken at intake
Comparative   
Notes   
Methodological quality
Item   Authors' judgement   Risk of bias   Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?  Yes      
Was a case‐control design avoided?  No      
Did the study avoid inappropriate exclusions?  Yes      
Did the study avoid inappropriate inclusions?  Yes      
Could the selection of patients have introduced bias?     Low risk   
Are there concerns that the included patients and setting do not match the review question?        Low concern
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?  Yes      
If a threshold was used, was it pre‐specified?  No      
Could the conduct or interpretation of the index test have introduced bias?     High risk   
Are there concerns that the index test, its conduct, or interpretation differ from the review question?        Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?  Yes      
Were the reference standard results interpreted without knowledge of the results of the index tests?  Unclear      
Could the reference standard, its conduct, or its interpretation have introduced bias?     Low risk   
Are there concerns that the target condition as defined by the reference standard does not match the question?        Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?  Yes      
Did all patients receive the same reference standard?  Yes      
Were all patients included in the analysis?  Yes      
Could the patient flow have introduced bias?     Low risk   
Peng 2020a
Study characteristics
Patient Sampling  Purpose: analyse the clinical features and imaging manifestations of COVID‐19Design: cross‐sectional, single‐centre, retrospective studyRecruitment: clinically suspected cases who were sent to hospital for screeningSample size: n = 86 (n = 11)Inclusion criteria: clinically suspected patientsExclusion criteria: not specified
Patient characteristics and setting  Facility cases: positive RT‐PCR via nasopharyngeal swabFacility controls: negative RT‐PCR via nasopharyngeal swab (1x)Country: ChinaDates: 23 January 2020‐16 February 2020Symptoms and severity: fever, cough, dyspnoea, sore throat, fatigue, systemic soreness, runny noseDemographics: M/F: total 39/47, cases: 5/6, controls 34/40Case group: mean age 40.73 ± 11.32 years, 5 men. Control group: mean age 39.67 ± 13.90 years, 34 menExposure history: 7/11 COVID‐19 patients (63.6%) had a history of travel to Hubei (5 Wuhan, 1 Huanggang, 1 Xiaogan), 2 patients had close contact with the COVID‐19 patients, and 2 taxi drivers
Index tests  Fever
Cough
Dyspnoea
Sore throat
Fatigue
Systemic soreness
Runny nose
Target condition and reference standard(s)  TC: SARS‐Cov‐2 infection
RS: RT‐PCR (nasopharyngeal swab)
Flow and timing  Time interval not specified
Comparative   
Notes   
Methodological quality
Item   Authors' judgement   Risk of bias   Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?  Unclear      
Was a case‐control design avoided?  Yes      
Did the study avoid inappropriate exclusions?  Unclear      
Did the study avoid inappropriate inclusions?  Unclear      
Could the selection of patients have introduced bias?     Unclear risk   
Are there concerns that the included patients and setting do not match the review question?        Unclear
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?  Yes      
If a threshold was used, was it pre‐specified?  No      
Could the conduct or interpretation of the index test have introduced bias?     High risk   
Are there concerns that the index test, its conduct, or interpretation differ from the review question?        Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?  Yes      
Were the reference standard results interpreted without knowledge of the results of the index tests?  Unclear      
Could the reference standard, its conduct, or its interpretation have introduced bias?     Low risk   
Are there concerns that the target condition as defined by the reference standard does not match the question?        Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?  Unclear      
Did all patients receive the same reference standard?  Yes      
Were all patients included in the analysis?  Yes      
Could the patient flow have introduced bias?     Low risk   
Rentsch 2020
Study characteristics
Patient Sampling  Purpose: diagnosis SARS‐CoV‐2 test positivesDesign: cross‐sectional, retrospective studyRecruitment: electronic health record data from the national Veterans Affairs Healthcare System ‐ national Corporate Data Warehouse (USA)Sample size: 3789 (585 cases)Inclusion criteria: all patients in the Veterans Affairs cohort, born between 1945 and 1965 and active in care, tested for COVID‐19 between 8 February and 30 March 2020Exclusion criteria: patients for whom results were pending (n = 93) or inconclusive (n = 33) were excluded
Patient characteristics and setting  Facility cases: tested positive for SARS‐CoV‐2Facility controls: tested negative for SARS‐CoV‐2Country: USADates: 8 February 2020‐30 March 2020Symptoms and severity: all patients who were tested were includedDemographics: median age overall: 65.7 years (IQR 60.5‐70.7) (cases: 66.1 years, controls: 65.6 years);gender overall (M%/F%): 90.2/9.8, cases 95.4/4.6, controls 89.2/10.8Exposure history: not specified (all over USA)
Index tests  Hypoxia (oxygen saturation ≤ 93%)
Body temperature (3 categories)
Target condition and reference standard(s)  TC: SARS‐CoV‐2 infection
RS: no data on reference PCR test used, multiple different reference tests used with unknown test characteristics (samples: nasopharyngeal swabs)
Flow and timing  Time interval maximum 2 days
Comparative   
Notes   
Methodological quality
Item   Authors' judgement   Risk of bias   Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?  Yes      
Was a case‐control design avoided?  Yes      
Did the study avoid inappropriate exclusions?  Yes      
Did the study avoid inappropriate inclusions?  Unclear      
Could the selection of patients have introduced bias?     Low risk   
Are there concerns that the included patients and setting do not match the review question?        Unclear
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?  Unclear      
If a threshold was used, was it pre‐specified?  Yes      
Could the conduct or interpretation of the index test have introduced bias?     Unclear risk   
Are there concerns that the index test, its conduct, or interpretation differ from the review question?        Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?  Unclear      
Were the reference standard results interpreted without knowledge of the results of the index tests?  Unclear      
Could the reference standard, its conduct, or its interpretation have introduced bias?     Unclear risk   
Are there concerns that the target condition as defined by the reference standard does not match the question?        Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?  Yes      
Did all patients receive the same reference standard?  Unclear      
Were all patients included in the analysis?  No      
Could the patient flow have introduced bias?     Low risk   
Song 2020b
Study characteristics
Patient Sampling  Purpose: to develop a tool for early diagnosis of SARS‐CoV2‐infected patientsDesign: cross‐sectional, retrospective, single‐centre (2 time frame study: training ‐ validation data set)Recruitment: 1311 patients who presented to the First Affiliated Hospital, School of Medicine, Zhejiang University with at least 1 SARS‐CoV‐2 RT‐PCR testSample size: n = 304 (73 cases) (= subset of the study including training dataset only)n = 95 (18 cases) (= validation dataset)Inclusion criteriaAll RT‐PCR‐positive cases; 1311
All RT‐PCR‐negative patients who came to the First Affiliated Hospital, School of Medicine, Zhejiang University and performed with at least 1 SARS‐CoV‐2 nucleic acid detection for analysis RT‐PCR
First 60% of negative outpatients sorted by 'Z‐A' based on Chinese first name from Qingchun District (training dataset), and then final 40% who presented (validation dataset)
Exclusion criteriaAsymptomatic patients without history of exposure but had strong willingness for detection
Patients with "important" missing data
Patient characteristics and setting  Facility cases: positive SARS‐CoV‐2Facility controls: negative SARS‐CoV‐2Country: ChinaDates: 20 January 2020‐05 February 2020Symptoms and severity: in positives: non‐severe (n = 31), including mild or moderate patients to severe (n = 42) including severe or critical patientsMild: patients had no pneumonia on imaging (CT)
Moderate: patients with symptoms and imaging examination showing pneumonia
Severe: patients meet any of the following:
respiratory rate ≥ 30/min
resting pulse SpO2 ≤ 93%
PaO2/FiO2 ≤ 300 mmHg (1 mmHg = 0.133 kPa)
multiple pulmonary lobes showing more than 50% progression of lesion in 24‐48 hours on imaging
Critical: patients meet any of the following:
respiratory failure requiring mechanical ventilation
shock
combination of other organ failure that requires admission to ICU
Demographics: M/F: cases 46/27, controls 104/127
median age: cases 53.0 years (43.5‐62.0) controls 34 years (29‐49)Exposure history: Wuhan‐related exposure and or close contact to confirmed COVID‐19 case: cases 40.7%, controls 57.5%
Index tests  Fever
Cough
Expectoration
Headache
Myalgia or fatigue
Chill
Rhinobyon/rhinorrhoea
Pharyngalgia
Dyspnoea
Diarrhoea
Nausea/vomiting
Temperature (maximum)
Body temperature
SpO2
Respiratory rate
Heart rate
Mean arterial pressure
Target condition and reference standard(s)  TC: SARS‐CoV‐2 infection
RS: RT‐PCR for SARS‐CoV‐2 (test not specified: "using emergency use authorization approved SARS‐CoV‐2 assays)" (following WHO protocol, 2 target RT‐PCR (ORF1 and N)
Flow and timing  Within 3 h for RS, first in‐hospital stay for index tests
Comparative   
Notes   
Methodological quality
Item   Authors' judgement   Risk of bias   Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?  No      
Was a case‐control design avoided?  Yes      
Did the study avoid inappropriate exclusions?  Unclear      
Did the study avoid inappropriate inclusions?  Yes      
Could the selection of patients have introduced bias?     Unclear risk   
Are there concerns that the included patients and setting do not match the review question?        Low concern
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?  Unclear      
If a threshold was used, was it pre‐specified?  No      
Could the conduct or interpretation of the index test have introduced bias?     High risk   
Are there concerns that the index test, its conduct, or interpretation differ from the review question?        Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?  Yes      
Were the reference standard results interpreted without knowledge of the results of the index tests?  Yes      
Could the reference standard, its conduct, or its interpretation have introduced bias?     Low risk   
Are there concerns that the target condition as defined by the reference standard does not match the question?        Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?  Yes      
Did all patients receive the same reference standard?  Yes      
Were all patients included in the analysis?  Yes      
Could the patient flow have introduced bias?     Low risk   
Sun 2020a
Study characteristics
Patient Sampling  Purpose: algorithm development for estimating risk COVID‐19Design: cross‐sectional, retrospective studyRecruitment: patients presenting at the designated national outbreak screening centre and tertiary care hospital in Singapore for SARS‐CoV‐2 testing. Patients were either self‐referred, referred from primary care facilities, or were at‐risk cases identified by national contact tracing efforts (recruited n = 991)Sample size: n = 788 (n = 54)Inclusion criteria: patients presenting to the centre:self‐referred
referred from primary care facilities
at‐risk cases identified by national contact tracing efforts
Exclusion criteria: PCR results not available at time of data collection ‐ no electronic medical records ‐ unavailable vital sign records
Patient characteristics and setting  Facility cases: positive SARS‐CoV2 RT‐PCR testFacility controls: all SARS‐CoV‐2 RT‐PCR results were negative (minimum 2 test negatives in high‐risk patients, minimum 1 test low‐risk patients)Country: SingaporeDates: 26 January 2020‐16 February 2020Symptoms and severity: 252 (33.2%) symptoms > 5 days at presentation, 75 (9.5%) any comorbiditybody temperature
heart rate
respiratory rate
systolic BP
diastolic BP
cough
sputum production
shortness of breath
rhinnorhoea or nasal congestion
sore throat
auscultation finding of pneumonia
other respiratory symptoms
gastrointestinal symptoms
Demographics: median age 34 years (range 7 years‐98 years, IQR 27‐45) (cases median 42 years, range 16‐79; controls 34 years (range 7‐98); M/F: 48.3%/51.7% F (cases M: 88 (88.9%))Exposure history: contact with a known COVID‐19 case (20.1% (32/54 cases (59.3%)); 126/734 controls (17.2%), contact with travellers from China (22.1%, 15/54 cases (27.8%); 42/734 controls (5.7%)), recent travel history, and visit to hospital in China within 14 days prior to symptom onset (0.8%)
Index tests  Body temperature
Heart rate
Respiratory rate
Systolic BP
Diastolic BP
Cough
Sputum production
Shortness of breath
Rhinnorhea or nasal congestion
Sore throat
Auscultation finding of pneumonia
Other respiratory symptoms
GI symptoms
Target condition and reference standard(s)  TC: SARS‐CoV‐2 infection
RS: SARS‐CoV‐2 2 commercial assays 2‐target (1 assay: Orf1ab and N ‐ other unclear) RT‐PCR
Flow and timing  Time interval not specified
Comparative   
Notes   
Methodological quality
Item   Authors' judgement   Risk of bias   Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?  Yes      
Was a case‐control design avoided?  No      
Did the study avoid inappropriate exclusions?  Yes      
Did the study avoid inappropriate inclusions?  Yes      
Could the selection of patients have introduced bias?     High risk   
Are there concerns that the included patients and setting do not match the review question?        High
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?  Yes      
If a threshold was used, was it pre‐specified?  No      
Could the conduct or interpretation of the index test have introduced bias?     High risk   
Are there concerns that the index test, its conduct, or interpretation differ from the review question?        Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?  Yes      
Were the reference standard results interpreted without knowledge of the results of the index tests?  No      
Could the reference standard, its conduct, or its interpretation have introduced bias?     Low risk   
Are there concerns that the target condition as defined by the reference standard does not match the question?        Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?  Unclear      
Did all patients receive the same reference standard?  Yes      
Were all patients included in the analysis?  Yes      
Could the patient flow have introduced bias?     Low risk   
Tolia 2020
Study characteristics
Patient Sampling  Purpose: diagnosis of acute SARS‐CoV‐2 infectionDesign: cross‐sectional, retrospective studyRecruitment: all patients presenting to 1 of 2 EDs, located at an urban teaching hospital, and academic quaternary medical centre, within the same healthcare system who had targeted testing based on clinician's decision during the initial 10 days of test availabilitySample size: n = 283 (29 cases)Inclusion criteria:patients presenting with symptoms related to COVID‐19 infection (fever and cough or shortness of breath)
travel within 14 days to countries with high rates of infection (at that time China, Iran, Italy, Japan, and South Korea) or
risk factors for infection complications (including age or comorbid conditions) or
the patient was a healthcare worker who could potentially expose others at risk and clinician made decision for testing
Exclusion criteria: not specified
Patient characteristics and setting  Facility cases: positive SARS‐CoV‐2 testFacility controls: negative SARS‐CoV‐2 test, visiting the same EDs and being testedCountry: USA (San Diego, CA)Dates: 10 March 2020‐19 March 2020Symptoms and severity:all patients presenting to ED who were eligible for targeted testing (= patients presenting with symptoms related to COVID‐19 infection (fever and cough or shortness of breath)
travel within 14 days to countries with high rates of infection (at that time China, Iran, Italy, Japan, and South Korea) or
risk factors for infection complications (including age or comorbid conditions) or
the patient was a healthcare worker who could potentially expose others at risk
comorbidities 101/235 (43.0%) (cases: 8/27 (29.6%), controls 93/208 (44.7%))
Demographics: age (< 18 years: 0.7%, 18‐64 years: 83.4%, > 65 years: 15.9%); gender: cases M/F%: 55.2/44.8; controls M/F%: 52.8/47.2; all M/F%: 53.0/47.0Exposure history: recent travel (5.5%), 90.6% symptom‐based criteria for testing, no known exposure history based
Index tests  Fever
Target condition and reference standard(s)  TC: SARS‐CoV‐2 infection
RS: Commercial RT‐PCR test ‐ ePLex SARS‐CoV‐2 test (nasopharyngeal swab)
Flow and timing  Probably no time interval between index test and RS, but not specified
Comparative   
Notes   
Methodological quality
Item   Authors' judgement   Risk of bias   Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?  Yes      
Was a case‐control design avoided?  Yes      
Did the study avoid inappropriate exclusions?  Unclear      
Did the study avoid inappropriate inclusions?  Yes      
Could the selection of patients have introduced bias?     Unclear risk   
Are there concerns that the included patients and setting do not match the review question?        Low concern
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?  Yes      
If a threshold was used, was it pre‐specified?  No      
Could the conduct or interpretation of the index test have introduced bias?     High risk   
Are there concerns that the index test, its conduct, or interpretation differ from the review question?        Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?  Yes      
Were the reference standard results interpreted without knowledge of the results of the index tests?  Unclear      
Could the reference standard, its conduct, or its interpretation have introduced bias?     Unclear risk   
Are there concerns that the target condition as defined by the reference standard does not match the question?        Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?  Unclear      
Did all patients receive the same reference standard?  Yes      
Were all patients included in the analysis?  Yes      
Could the patient flow have introduced bias?     Low risk   
Wee 2020
Study characteristics
Patient Sampling  Purpose: to analyse OTDs as a diagnostic criterion for COVID‐19Design: cross‐sectional, prospective single‐centre studyRecruitment: all suspected cases presenting to the EDSample size: n = 870 (cases = 154)Inclusion criteria:presence of respiratory symptoms and suspicious epidemiological links or travel history or
new onset OTD
Exclusion criteria: not specified
Patient characteristics and setting  Facility cases: positive RT‐PCR for 2019‐nCovFacility controls: negative RT‐PCR for 2019‐nCovCountry: SingaporeDates: 26 March 2020‐10 April 2020Symptoms and severity: loss of sense of smell/tasteDemographics: not specifiedExposure history: close contact of a confirmed COVID‐19 case: cases 42/112, controls 37/679
Index tests  Loss of sense of smell/taste
Target condition and reference standard(s)  TC: SARS‐Cov‐2 infection
RS: RT‐PCR (oropharyngeal swabs)
Flow and timing  Time interval: same day
Comparative   
Notes   
Methodological quality
Item   Authors' judgement   Risk of bias   Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?  Unclear      
Was a case‐control design avoided?  Yes      
Did the study avoid inappropriate exclusions?  Unclear      
Did the study avoid inappropriate inclusions?  Yes      
Could the selection of patients have introduced bias?     Low risk   
Are there concerns that the included patients and setting do not match the review question?        Low concern
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?  Yes      
If a threshold was used, was it pre‐specified?  No      
Could the conduct or interpretation of the index test have introduced bias?     High risk   
Are there concerns that the index test, its conduct, or interpretation differ from the review question?        Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?  Yes      
Were the reference standard results interpreted without knowledge of the results of the index tests?  Unclear      
Could the reference standard, its conduct, or its interpretation have introduced bias?     Low risk   
Are there concerns that the target condition as defined by the reference standard does not match the question?        Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?  Yes      
Did all patients receive the same reference standard?  Yes      
Were all patients included in the analysis?  Yes      
Could the patient flow have introduced bias?     Low risk   
Yan 2020a
Study characteristics
Patient Sampling  Purpose: to evaluate association of patient‐reported symptoms with a focus on sense of smell and taste and SARS‐CoV‐2 infectionDesign: internet survey of patients after presentation to a single‐centreRecruitment: email invitation with 1 phone call follow‐up to everyone who was tested for COVID‐19 between 3 March 2020 and 29 March 2020Sample size: n = 262 (cases: 59)Inclusion criteria:adult patients who presented to the institution and got tested for COVID‐19
analysis on responders to email survey (responses: cases 59/102, controls 203/1378)
Exclusion criteria:
Patient characteristics and setting  Facility cases: SARS‐CoV‐2‐positiveFacility controls: SARS‐CoV‐2‐negativeCountry: USA, San DiegoDates: 3 March 2020‐29 March 2020Symptoms and severity:larger representation of ambulatory patients (higher response rate to survey)
severity ‐ hospital admission: cases 4/59, controls 14/203
Demographics: adults only, M/F: cases 29/29, controls 69/132Exposure history: not specified
Index tests  Fatigue
Loss of taste
Fever
Loss of sense of smell
Cough
Headache
Myalgia
Dyspnoea
Diarrhoea
Nasal obstruction
Sore throat
Rhinorrhoea
Nausea
Target condition and reference standard(s)  TC: SARS‐CoV‐2 infection
RS: PCR for SARS‐CoV‐2 (sample not specified)
Flow and timing  PCR taken at presentation, not specified when the questionnaire was sent. Patients had to list their symptoms at presentation.
Comparative   
Notes   
Methodological quality
Item   Authors' judgement   Risk of bias   Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?  Yes      
Was a case‐control design avoided?  Yes      
Did the study avoid inappropriate exclusions?  Unclear      
Did the study avoid inappropriate inclusions?  Unclear      
Could the selection of patients have introduced bias?     Unclear risk   
Are there concerns that the included patients and setting do not match the review question?        Unclear
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?  No      
If a threshold was used, was it pre‐specified?  No      
Could the conduct or interpretation of the index test have introduced bias?     High risk   
Are there concerns that the index test, its conduct, or interpretation differ from the review question?        Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?  Unclear      
Were the reference standard results interpreted without knowledge of the results of the index tests?  Yes      
Could the reference standard, its conduct, or its interpretation have introduced bias?     Low risk   
Are there concerns that the target condition as defined by the reference standard does not match the question?        Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?  Unclear      
Did all patients receive the same reference standard?  Yes      
Were all patients included in the analysis?  Yes      
Could the patient flow have introduced bias?     Unclear risk   
Yang 2020d
Study characteristics
Patient Sampling  Purpose: to identify differences in CT imaging and clinical features between COVID‐19 and
influenza pneumonia in the early stage, and to identify the most valuable features in the differential
diagnosisDesign: diagnostic case‐control study, retrospective multicentre with historic control groupRecruitment: cases: confirmed SARS‐CoV‐2 patients; controls: influenza pneumonia patients (1 January 2015‐30 September 2019 from 2 hospitals)Sample size: n = 121 (cases = 73)Inclusion criteria: patients confirmed with SARS‐CoV‐2; controls: patients who had 9 respiratory pathogen IgM antibody tested from January 2015‐September 2019Exclusion criteria: cases: not specifiedcontrols:parainfluenza
respiratory syncytial virus
adenovirus
Legionella spp
Mycoplasma pneumoniae
Chlamydia pneumoniae
Coxiella burnetii
aspiration pneumonia
radiation pneumonia
pulmonary contusion
pulmonary oedema
neoplasm
No CT date, no clinical date
Patient characteristics and setting  Facility cases: positive RT‐PCR for 2019‐nCovFacility controls: influenza pneumoniaCountry: ChinaDates: 1 January 2020‐15 February 2020Symptoms and severity: all patients in early stages of COVID‐19 or influenza pneumoniaDemographics: M/F: cases 41/32, controls 30/18
mean age: cases 41.9, controls 40.4Exposure history: not specified
Index tests  Body temperature
Cough
Fatigue
Sore throat
Stuffy and runny nose
Target condition and reference standard(s)  TC: COVID‐19 pneumonia
RS: RT‐PCR (sample not specified)
Flow and timing  Time interval unclear
Comparative   
Notes  Overlaps with Chen X 2020
Methodological quality
Item   Authors' judgement   Risk of bias   Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?  Yes      
Was a case‐control design avoided?  No      
Did the study avoid inappropriate exclusions?  Unclear      
Did the study avoid inappropriate inclusions?  No      
Could the selection of patients have introduced bias?     High risk   
Are there concerns that the included patients and setting do not match the review question?        High
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?  Unclear      
If a threshold was used, was it pre‐specified?  No      
Could the conduct or interpretation of the index test have introduced bias?     High risk   
Are there concerns that the index test, its conduct, or interpretation differ from the review question?        Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?  Yes      
Were the reference standard results interpreted without knowledge of the results of the index tests?  Unclear      
Could the reference standard, its conduct, or its interpretation have introduced bias?     High risk   
Are there concerns that the target condition as defined by the reference standard does not match the question?        High
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?  Unclear      
Did all patients receive the same reference standard?  Yes      
Were all patients included in the analysis?  Yes      
Could the patient flow have introduced bias?     Unclear risk   
Zhao 2020a
Study characteristics
Patient Sampling  Purpose: to compare and assess the clinical features of COVID‐19 pneumonia with features in non‐COVID‐19 pneumonia patientsDesign: diagnostic case control, retrospective studyRecruitment: patients with similar duration between symptom onset to admission were selected as controlsSample size: n = 34 (n = 15)Inclusion criteria: admitted pneumonia cases with a history of travel to Hubei or exposure to a PCR SARS‐CoV‐2‐confirmed‐positive patientExclusion criteria: not specified
Patient characteristics and setting  Facility cases: single sputum or throat swab test RT‐PCR‐positive pneumoniaFacility controls: for non‐COVID‐19 confirmation: 3 consecutive negative throat swabs or sputum sampling every other day during first 7 days of admissionCountry: China, AnhuiDates: 23 January 2020‐5 February 2020Symptoms and severity:fever
cough
sore throat
headache
fatigue
diarrhoea
chest tightness
abnormal lung auscultation
Demographics: mean age (cases/controls): 48 (IQR 27~56)/35 (IQR 27~46) in COVID‐19 and non‐COVID‐19 patients, respectively; F/M (cases/controls): 8 (42.11%)Exposure history: all patients had a history of exposure to confirmed cases of 2019‐nCoV or travel to Hubei before illness. Investigators interviewed each patient and their relatives, where necessary, to determine exposure or close contact histories during the 2 weeks before the illness onset
Index tests  Fever
Cough
Sore throat
Headache
Fatigue
Diarrhoea
Chest tightness
Abnormal lung auscultation
Target condition and reference standard(s)  TC: COVID‐19 pneumonia
RS: real‐time RT‐PCR (unknown assay) (sample: throat swabs or/and sputa)
Flow and timing  Time interval not specified
Comparative   
Notes   
Methodological quality
Item   Authors' judgement   Risk of bias   Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?  No      
Was a case‐control design avoided?  No      
Did the study avoid inappropriate exclusions?  Unclear      
Did the study avoid inappropriate inclusions?  Yes      
Could the selection of patients have introduced bias?     High risk   
Are there concerns that the included patients and setting do not match the review question?        High
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?  Yes      
If a threshold was used, was it pre‐specified?  No      
Could the conduct or interpretation of the index test have introduced bias?     High risk   
Are there concerns that the index test, its conduct, or interpretation differ from the review question?        Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?  Yes      
Were the reference standard results interpreted without knowledge of the results of the index tests?  Yes      
Could the reference standard, its conduct, or its interpretation have introduced bias?     Unclear risk   
Are there concerns that the target condition as defined by the reference standard does not match the question?        Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?  Unclear      
Did all patients receive the same reference standard?  Yes      
Were all patients included in the analysis?  Yes      
Could the patient flow have introduced bias?     Unclear risk   
Zhu 2020b
Study characteristics
Patient Sampling  Purpose: description of initial clinical features in patients with suspected and confirmed SARS‐CoV‐2 infectionDesign: cross‐sectional, retrospective studyRecruitment: all patients with suspected COVID‐19 who presented to the ED of the First Affiliated Hospital of USTC and the Infectious Hospital of the First Affiliated Hospital of USTC for the first timeSample size: n = 116 (32 cases)Inclusion criteria:patients defined as suspected SARS‐CoV‐2 infection based on guidelines for the diagnosis and treatment of pneumonia caused by novel coronavirus infection (trial version III)
presentation to, clinical observation and quarantine in our ED
nucleic acid amplification test performed in the ED
Exclusion criteria: transfer from another hospital or previous visit to our hospital and previous diagnosis of COVID‐19
Patient characteristics and setting  Facility cases: positive nucleic acid amplification test on admission or 24 h laterFacility controls: SARs‐CoV‐2 PCR test negativeCountry: China, AnhuiDates: 24 January 2020‐20 February 2020Symptoms and severity: all suspected COVID‐19 patients included; days since onset of symptoms median 5 (IQR 2‐7)Demographics: median age: all: 40 years (IQR 27‐53), cases: 46 years (IQR 35‐52), controls: 35 years (IQR 27‐53); gender distribution M%/F%: all 46/54, cases 47/53, controls 46/54Exposure history: no specific exposure history common to all patients with suspected disease: 8 (25%) diagnosed patients had visited Wuhan in the previous 2 weeks and 12 (38%) had been exposed to patients with infection in the previous 2 weeks
Index tests  Fever
Cough
Myalgia or fatigue
Experctoration
Chest stuffiness (congestion)
Haemoptysis
Headache
Diarrhoea
Target condition and reference standard(s)  TC: SARS‐CoV‐2 infection
RS: nucleic acid amplification test not further specified (twice in case negatives) (samples: swabs, origin not specified)
Flow and timing  Index tests and RS both taken on admission or after 24 h
Comparative   
Notes   
Methodological quality
Item   Authors' judgement   Risk of bias   Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?  Yes      
Was a case‐control design avoided?  Yes      
Did the study avoid inappropriate exclusions?  Yes      
Did the study avoid inappropriate inclusions?  Yes      
Could the selection of patients have introduced bias?     Low risk   
Are there concerns that the included patients and setting do not match the review question?        Low concern
DOMAIN 2: Index Test (All tests)
Were the index test results interpreted without knowledge of the results of the reference standard?  Yes      
If a threshold was used, was it pre‐specified?  No      
Could the conduct or interpretation of the index test have introduced bias?     High risk   
Are there concerns that the index test, its conduct, or interpretation differ from the review question?        Low concern
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?  Yes      
Were the reference standard results interpreted without knowledge of the results of the index tests?  Unclear      
Could the reference standard, its conduct, or its interpretation have introduced bias?     Unclear risk   
Are there concerns that the target condition as defined by the reference standard does not match the question?        Low concern
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?  Yes      
Did all patients receive the same reference standard?  Yes      
Were all patients included in the analysis?  Yes      
Could the patient flow have introduced bias?     Unclear risk   
BP: blood pressure; COPD: constructive obstructive pulmonary disease; COVID‐19: coronavirus disease 2019; CT: computed tomography; ED: emergency department; F: female; FiO2: fraction of inspired oxygen; GI: gastrointestinal; ICU: intensive care unit; IgM: immunoglobulin M;IQR: interquartile range; M: male; NCP: novel coronavirus pneumonia; OTD: olfactory and taste disorder; PaO2: partial pressure of oxygen; RS: reference standard; RT‐PCR: reverse transcription polymerase chain reaction; SARS‐CoV‐2: severe acute respiratory syndrome coronavirus 2; SD: standard deviation;SpO2: oxygen saturation; TC: target condition; WBC: blood white blood cell; WHO: World Health Organization; 2019‐nCoV: 2019 novel coronavirus

Characteristics of excluded studies [ordered by study ID]
Study  Reason for exclusion
Guan 2020  SARS‐CoV‐2‐positive cases only
Soares 2020  No data
Song 2020  SARS‐CoV‐2‐positive cases only
Wang 2020  No data

Contributions of authors
JD, JDi, YT, CD, ML, RS, LH, AV, DE, and SD contributed clinical, methodological and/or technical expertise to drafting the protocol. JD co‐ordinated contributions from all co‐authors and drafted the protocol. ML drafted the QUADAS‐2 criteria. AVDB oversaw the overall progress of this review, drafted the manuscript and participated in the selection and data extraction. TS participated in the data extraction, analyses and drafting of the manuscript. JD and BH also participated in the data extraction, interpretation of the findings and commented on the manuscript.

Sources of support

Internal sources
Liverpool School of Tropical Medicine, UK
University of Birmingham, UK

External sources
Department for International Development, UK
Project number: 300342‐104
National Institute for Health Research (NIHR), UK
NIHR Birmingham Biomedical Research Centre at the University Hospitals Birmingham NHS Foundation Trust and the University of Birmingham, UK

Declarations of interest
Thomas Struyf: none known
Jonathan J Deeks: none known
Jacqueline Dinnes: none known
Yemisi Takwoingi: none known
Clare Davenport: none known
Mariska MG Leeflang: none known
René Spijker: the Dutch Cochrane Centre (DCC) has received grants for performing commissioned systematic reviews. In no situation, the commissioner had any influence on the results of the work.
Lotty Hooft: none known
Devy Emperador: is employed by FIND. FIND has several clinical research projects to evaluate multiple new diagnostic tests against published Target Product Profiles that have been defined through consensus processes. These studies are for diagnostic products developed by private sector companies who provide access to know‐how, equipment/reagents, and contribute through unrestricted donations as per FIND policy and external SAC review.
Sabine Dittrich: is employed by FIND with funding from DFID and Australian Aid. FIND is a global non‐for profit product development partnership and WHO Diagnostic Collaboration Centre. It is FIND’s role to accelerate access to high quality diagnostic tools for low resource settings and this is achieved by supporting both R&D and access activities for a wide range of diseases, including COVID‐19. .FIND has several clinical research projects to evaluate multiple new diagnostic tests against published Target Product Profiles that have been defined through consensus processes. These studies are for diagnostic products developed by private sector companies who provide access to know‐how, equipment/reagents, and contribute through unrestricted donations as per FIND policy and external SAC review.
Julie Domen: none known
Sebastiaan Horn: none known
Ann Van den Bruel: none known