Just How Much Coronavirus We Encounter May Be Key to Outcome

(Bloomberg) -- Face masks and social distancing may help make the coronavirus less lethal for those who catch it by limiting the amounts they’re exposed to.

Two new studies released Thursday point in that direction. One shows the amount of coronavirus that hospital patients in Detroit carried in their nose declined between April and June as people adopted masks and other public-health measures -- and that the drop was associated with a decrease in death rates. Another study, from Italy, found that as the so-called viral load declined, so did severe cases.

The findings, released at a conference on the new disease, suggest that face masks and other measures lead to milder disease even when they fail to thwart transmission. By doing so, they buttress a theory put forth this month in the New England Journal of Medicine, where researchers wrote that masks could act as a crude form of immunization against the virus.

“Lockdown measures had an impact not only in the absolute number of infected people but also on the severity of clinical manifestations,” Chiara Piubelli, a molecular biologist at Sacro Cuore-Don Calabria hospital near Verona, said in a presentation.

In the Italian study, which included 373 patients diagnosed with Covid-19 between early March and the end of May, the viral load remained about the same in patients admitted to intensive care, while it declined in those who weren’t admitted.

The Detroit research, based on the analysis of 708 nasal samples, found that almost half of patients with a high viral load died, compared with only 14% for those with a low amount of virus.

“Social distancing measures and widespread use of face masks may have contributed to a decrease in the exposure to the virus,” wrote the researchers, led by Said El Zein of Detroit Medical Center. “This may have future implications on public-health measures and infection-control practices.”

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