TABLE 2.

Efficacy of convalescent-phase serum or plasma in various epidemics

Epidemic	Mortality reduction (%)	Type of studya	Reference
1918 Influenza	∼20	Meta-analysis	54
Argentine hemorrhagic fever	93	RCT	55
SARS-CoV	73	Case series	57
2009 Influenza H1N1	63	Quasi-RCT	78
Ebola virus	8–18	RCT	59
Seasonal influenza	0	RCT	58
COVID-19	∼35 (range, 0–60)	Meta-analysis of dozens of studies	4

^aRCT, randomized controlled trial.