Fig. 2

Scatterplot of Vaccine efficacy/effectiveness (VE) % against SARS-CoV-2 infection (A), symptomatic COVID-19 (B) and severe COVID-19 (C) plotted according to time from the second dose for mRNA vaccines and one dose of adenovirus vector-based vaccine. Each circle represents a study, and its size is proportional to the study’s sample size and annotated according to vaccine type. Effectiveness estimates include studies that estimated efficacy. The red line represents the fitted mean VE using the natural cubic spline model. The horizontal blue line represents the 50% protection level stipulated by the WHO [7]