Study		Exclusion reasons	Remarks	Reference(s)
Gritti et al., 2020	single-arm	inadequate or absent control group		Gritti et al. medRxiv 10.1101/2020.04.01.20048561
Holt, 2020	retrospective cohort	other	no CI reported	Holt, Gregory E 10.21203/rs.3.rs-39875/v1
Klopfenstein, 2020	retrospective cohort	other	major flaws in the method	Klopfenstein T International Journal of Infectious Diseases 10.1016/j.ijid.2020.08.024