Figure 1.

Flowchart of the study selection process.

*The study conducted by Goldshtein et al.[12] included both vaccine effectiveness and adverse reactions to vaccines.

**The four included articles contained six studies. The article by Dagan et al. included two studies: Dagan et al.[11] (documented infection) and Dagan et al.[11] (symptomatic infection). The article by Paixao et al.[14] also included two studies: Paixao et al.[14] (symptomatic infection) and Paixao et al.[14] (severe infection).