A new theory proposed by infectious disease specialists at UC San Francisco Dr. Monica Gandhi and Dr. George Rutherford in the New England Journal of Medicine claims that if you are infected with COVID-19 through a mask, the face covering can limit the severity of your symptoms. They note that masks reduce the number of viral particles in the air, which leads to a lower dose of the virus, if infected. The immune system has a better chance of suppressing a smaller number of viral particles before they duplicate.
Along with examples from history, Dr. Gandhi and Dr. Rutherford point to specific trends we have seen during the COVID-19 pandemic to support their theory:
- The CDC reports that the typical rate of asymptomatic COVID-19 infection is 40%, but comparing an outbreak on an Argentinean cruise ship versus the Diamond Princess cruise ship docked in Yokohama, Japan shows variation in this. The Argentinean cruise ship supplied surgical masks to staff and passengers and as a result, 81% of infected people never developed symptoms. The Diamond Princess, however, were without masks and only 18% of people infected were asymptomatic.
- In two recent outbreaks in U.S. food processing plants (Oregon seafood and Arkansas chicken processing plant) all employees in the plant were provided masks and required to wear them each day. Of the 500 people who were infected, 95% were asymptomatic and 5% experienced mild to moderate symptoms.
- In countries where mask wearing was already common, like South Korea, Japan, Singapore, etc. rates of death and severe illness has remained low in comparison to the rest of the world.
Dr. Gandhi and Dr. Rutherford close with the idea that in order to combat the pandemic, severity of disease and transmission rates must be lessened- and there is increasing evidence that population-wide mask wearing would benefit both of these components.
Read the full article in the New England Journal of Medicine here.