The commentary, published in the New England Journal of Medicine, advances the unproven but promising theory that universal face mask wearing might be helping to reduce the severity of the virus and ensuring that a greater proportion of new infections are asymptomatic.
If this hypothesis is borne out, the academics argue, then universal mask-wearing could become a form of variolation (inoculation) that would generate immunity and “thereby slow the spread of the virus in the United States and elsewhere” as the world awaits a vaccine.
It comes as increasing evidence suggests that the amount of virus someone is exposed to at the start of infection – the “infectious dose” – may determine the severity of their illness. Indeed, a large study published in the Lancet last month found that “viral load at diagnosis” was an “independent predictor of mortality” in hospital patients.
Wearing masks could therefore reduce the infectious dose that the wearer is exposed to and, subsequently, the impact of the disease, as masks filter out some virus-containing droplets.