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 V_a .

^†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).