BackgroundDuring the COVID-19 pandemic, the number of studies listed in The National Library of Medicine registry (ClinicalTrials.gov) and preprints in medRxiv for COVID-19 has grown rapidly. In this study, we clarified the publication trends of randomized controlled trials (RCTs) and systematic reviews (SRs) regarding COVID-19. Methods: We conducted a cross-sectional study by investigating the number of SRs and RCTs on topics related to COVID-19 practice published in PubMed and medRxiv between January 1 and June 30, 2020. We calculated the ratio of the number of RCTs to that of SRs for this study period, as in a previous study. Results: The SR/RCT ratio in PubMed increased from 9.0 in March to 102 in June. In medRxiv, the SR/RCT ratio rose from 7.7 in March to 16.5 in June Discussion: The SR/RCT ratio increased and was much higher than that of 0.871 in 2017 found in a previous review of all medical research. During the study period, the trend in the COVID-19 publications comprised a more rapid increase in the number of SRs than RCTs
