Extended Data Fig. 8: Validation of the results for the pre-omicron era using a cohort study design.

The figure compares the main analysis results obtained using the test-negative design to the results obtained using the cohort study design. The comparisons include: a) overall effectiveness of infection in preventing reinfection, b) overall effectiveness of infection in preventing severe, critical, or fatal COVID-19 upon reinfection, c) overall effectiveness of infection in preventing reinfection for each of vaccinated and unvaccinated individuals, d) effectiveness of infection in preventing reinfection by time since prior infection, and e) effectiveness of infection in preventing severe, critical, or fatal COVID-19 upon reinfection by time since prior infection. Analysis using the test-negative design includes 384,231 and 684,257 independent samples for cases and controls, respectively. Analysis using the cohort design includes 339,019 independent samples for each of the primary infection and uninfected cohorts. Data are presented as effectiveness point estimates and corresponding 95% confidence intervals. Error bars indicate the 95% confidence intervals. Measures were not adjusted for multiplicity.