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. 2021 Oct 11;215(9):427–432. doi: 10.5694/mja2.51263
Efficacy Vaccine
Pfizer AstraZeneca
Susceptibility to infection (V a) 0.76* 0.48 , 20
Symptomatic COVID‐19 in infected people (V s) 0.5 , 19 , 21 0.37 , 19 , 20
Symptomatic COVID‐19 (V e) 0.88 5 , 13 0.67 5 , 13 , 22
Disease transmission by an infected person (V t) 0.5 23 0.5 23
Hospitalisation and death (V m) 0.5 24 0.8 24

COVID‐19 = coronavirus disease 2019; SARS‐CoV‐2 = severe acute respiratory syndrome coronavirus 2.

*

Estimated by solving the expression 1 – V e = (1 – V a)(1 – V s), for Va .

These values are chosen to achieve vaccine efficacy of 0.67 in symptomatic infection and 0.22 for asymptomatic infection reported in reference 20.

This value is chosen to achieve vaccine efficacy of 0.9 for symptomatic infection and 0.8 for asymptomatic infection reported in reference 19 (based on non‐Delta variants).