Materials and methods
Data collection, manipulation, calculations, and visualization were performed using the R (version 3.6.3) programming language (R Foundation, Vienna, Austria). We collected data on COVID-19 publications using the R PubMed API called "easyPubMed" on 9th of July 2020 [2]. We set the following query conditions: date between the 31st of December 2019 and 30th of June 2020, and search terms: "novel coronavirus," "coronavirus Wuhan," "SARS-CoV-2," "COVID-19." We identified articles with or without abstract, original articles, reviews, meta-analyses, and guidelines.
We ranked countries based on the number of articles with at least one author coming from each country. We confronted the ranking of countries with the highest number of articles on COVID-19 with SCImago ranking of countries with the highest medical researchers' productivity in 2019 [3]. Moreover, we conducted the Spearman rank correlation test between the number of articles in each country and:
(a) the total number of COVID-19 cases per one million citizens before the 1st of July 2020 [4],
(b) the total number of deaths related to COVID-19 per one million citizens before the 1st of July 2020 [5], and
(c) Human Development Index (HDI) for 2018 [6].
We choose the R Spearman correlation rank test because the data we analyzed is presented in interval scale (e.g., HDI is an artificial index, and similarly like BMI, non-parametrical tests should be preferred). Our data also had many outliers, which is other indication of Spearman correlation rank usefulness. We matched journal names with the SCImago journal database that contains information on the journal category [7]. For instance, "The Lancet Infectious Diseases" is categorized as "Infectious Diseases" journal, while "Clinical Microbiology Reviews" as one of the following: "Epidemiology," "Infectious Diseases," "Microbiology (medical)," or "Public Health, Environmental and Occupational Health" journal. We counted the number of reports on COVID-19 in journals from each category and presented categories with the highest number of publications.