Figure 1.

Vaccine efficacy and study design

(A) Adjusted hazard ratios with 95% confidence intervals for PCR confirmed cases by interval after first and second doses of vaccination (source: SIREN study). HCWs underwent regular asymptomatic PCR screening (n = 25,066; negative cohort, 16,423; positive cohort, 8,643) with follow-up to 95 days after the first dose of the BNT162b2 vaccine. The hazard ratios are adjusted (including for age, ethnicity, comorbidities, and region), with full methodology described (Hall et al., 2021).

(B) Schematic showing the dosing strategies of short and long vaccine intervals and phlebotomy time points.