Masks Protect You and Others from Covid

Monica Gandhi MD, MPH is Professor of Medicine and Associate Division Chief (Clinical Operations/Education) of the Division of HIV, Infectious Diseases, and Global Medicine at UCSF/ San Francisco General Hospital. 

As the COVID-19 pandemic has received a great deal of attention, we'll discuss for one of the first times the hypothesis that universal masking reduces the “inoculum” or dose of the virus for the mask-wearer, leading to more mild and asymptomatic infection manifestations.  Masks, depending on type, filter out the majority of viral particles, but not all. We first discuss the near-century old literature around the viral inoculum and severity of disease We will then include examples of rising rates of asymptomatic infection with population-level masking, including in closed settings (e.g. cruise ships), outbreaks, and countrieswith and without universal masking. Asymptomatic infections may be harmful for spread but could actually be beneficial if they lead to higher rates of exposure. Exposing society to SARS-CoV-2 without the unacceptable consequences of severe illness with public masking could lead to greater community-level immunity and slower spread as we await a vaccine