Table 1.

Production of coronavirus articles by time period

Number of publications with author affiliation details
Source	Pre-COVID-19 (January 1 2018–December 31 2019)	COVID-19
		Total	Period 1	Period 2	Period 3
Published items	6,980	74,771	2,728	32,420	39,623
Published items (formal)	5,292	57,833	1,508	22,817	33,508
Preprints (arXiv / bioRxiv / medRxiv / ChemRxiv)		12,744	2,147	6,718	3,879
Combined	6,980	87,515	4,875	39,138	43,502

COVID-19 is separated into 3 Periods: Period I, from January 1 to April 8; Period II, from April 9 to July 12; and Period III, from July 13 to October 5. Periods 1–3 for preprints are almost the same as published items except for the separating date between Period I and Period II is April 25. Formal publications are defined as articles, journal articles, and research support (in PMC) that are published in journals