Fig. 2: Estimated VE and Placebo Incidence Across Regions in the ENSEMBLE Trial.
From: Association between COVID-19 vaccine efficacy and epidemic force of infection
VE was estimated using a Cox proportional hazards model without covariates, with confidence intervals calculated via the delta method. Placebo incidence was defined as the number of cases divided by the total person-years of follow-up in the placebo group.
