Mask mandates have been a globally used epidemiologic intervention during the ongoing COVID-19 (coronavirus disease 2019) pandemic. Although there is extensive supporting literature on the use of facemask to reduce infection rates, its effect on the individual and course of disease has remained controversial. The purpose of this study was to find if mandatory masking influences the case fatality rate. This study used data on case updates, mask mandates, and demographic status related to the Kansas state, USA. The data were analyzed using a parallelization approach based on county-level data.

The results showed that in Kansas during the summer of 2020, the counties with mask mandate had significantly higher case fatality rates compared to counties without mask mandate, with a risk ratio of 1.85 [1.51-2.10] for death with COVID-19.

Even after adjusting for the number of ‘protected persons’, i.e., the number of persons who were not infected in the mask-mandated group compared to the no-mask group, the risk ratio remained significantly high at 1.52 [1.24-1.72]. By analyzing the excess mortality in Kansas, this study determines that over 95% of this effect can solely be attributed to COVID-19. The cause of this trend and the possible connection between long-term effects associated with SARS-CoV-2 and facemasks are explained in the theory herein by the 'foegen effect'; i.e., deep reinhalation of pure virions caught in the facemasks as droplets can worsen the prognosis.

This finding suggests that the use of facemasks in COVID-19 pandemic did contribute to an increase in the death toll counterintuitive of its purpose, making mask mandates a highly debatable epidemiologic intervention.