2.1. Search strategy

The relevant medical literature was searched by two authors (SC and DR) for studies reporting on the incidence and outcomes of postvaccination COVID‐19 infection among HCWs. A systematic and detailed search was run in August 2021 in Ovid EBM Reviews, ClinicalTrials.gov, Ovid Embase (1974 + ), Ovid Medline (1946+ including epub ahead of print, in‐process and other non‐indexed citations), Scopus (1970 + ), Web of Science (1975 + ), and Google Scholar. A literature search was performed to include studies published in all languages, and in the case of non‐English studies, an electronic language translation service was used to convert the text to English. An example search strategy using EMBASE is presented as Appendix‐S1. Articles were included if data with regard to incidence of postvaccination COVID‐19 infection was presented. Only cohort studies were eligible for inclusion. All other study designs including, case series of less than 10 patients, case reports, review articles, and guidelines were excluded.

As the included studies were observational in design, the MOOSE (Meta‐analyses Of Observational Studies in Epidemiology) Checklist was followed 9 and is provided as Appendix‐S2. PRISMA Flowchart for study selection 10 is provided as Appendix‐S3. Reference lists of evaluated studies were further examined to identify other studies of interest.