The effect of face masks on Covid transmission: A meta-analysis

The effect of face masks on Covid-19 transmission is crucial for the health of populations. The effectiveness of face masks in reducing the transmission of Covid-19 varies across primary evidence. To perform a quantitative meta-analysis, we collected 258 estimates from 44 primary studies together with more than 30 variables reflecting the differences among these studies. We examine publication bias by implementing various statistical tests, revealing mild evidence for the phenomenon. Our contribution to other meta-analyses on this topic involves the use of Bayesian and Frequentist model averaging to identify the drivers behind the heterogeneity of the estimates. The results indicate that temperature, geographical latitude, and panel data structure increase the risk of transmission associated with maskwearing. Furthermore, a positive effect is identified for the healthcare setup. In contrast, wearing masks during aerosol-generating procedures decreases the risk of transmission.