Fig. 1
Flowchart of the study cohort. Participants were excluded in case of a missing signed informed consent, not sending samples (drop outs), or a missing sample at a month post 2nd vaccination (T2). For further data analysis, samples taken outside the time window around the predefined timepoints post vaccination were excluded, participants already infected with SARS-CoV-2 before vaccination and participants missing data on co-morbidities and other health parameters since round 6 of the Doetinchem cohort study were also excluded