. 2021 Oct 26;75(1):e764–e773. doi: 10.1093/cid/ciab914

Table 1.

Methods for Measuring Vaccine Efficacy Against Infection, Symptomatic Infection and Asymptomatic Infection in the COVID-19 Phase III Trials

Vaccine Efficacy Outcome	Measurement Method	Vaccine^b
Vaccine Efficacy Outcome	Measurement Method	Spike Protein	Whole Virus^c
Symptomatic infection	PCR swabbing upon self-reporting of symptoms	Oxford-AstraZeneca ChAdOx1 Janssen Ad26.COV2.S GRI Sputnik V Pfizer-BioNTechBNT162b2 Moderna mRNA-1273 Novavax NVX-CoV2373	Bharat Biotech Covaxin Sinopharm BBIBP-CorV Sinovac CoronaVac
Asymptomatic infection	Regular PCR swabbing regardless of symptoms	Oxford-AstraZeneca ChAdOx1^a	Bharat Biotech Covaxin
Asymptomatic infection	Serology testing at prespecified time intervals	Oxford-AstraZeneca ChAdOx1 Janssen Ad26.COV2.S Pfizer-BioNTechBNT162b2 Moderna mRNA-1273 Novavax NVX-CoV2373
Overall infection	Serologically confirmed asymptomatic infections + PCR-confirmed symptomatic infections	Janssen Ad26.COV2.S Moderna mRNA-1273 Novavax NVX-CoV2373	Sinovac CoronaVac
	Serologically confirmed asymptomatic infections + serologically confirmed symptomatic infections	Oxford-AstraZeneca ChAdOx1 Janssen Ad26.COV2.S Moderna mRNA-1273 GRI Sputnik V Novavax NVX-CoV2373	Sinovac CoronaVac
	PCR-confirmed asymptomatic infections + PCR-confirmed symptomatic infections	Oxford-AstraZenecaChAdOx1	Bharat Biotech Covaxin

Abbreviations: COVID-19, coronavirus disease 2019; GRI, Gamaleya Research Institute; mRNA, messenger RNA; PCR, polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.

COV002 (UK) trial only.

Vaccines only listed where measurement approach has been reported. Trial numbers provided in Supplementary Table 1.

For vaccines based on the whole virus, it may be possible to infer infection via a rise in SARS-CoV-2 antibodies following a period after vaccination.