Pre-, asymptomatic COVID cases lead to half of transmissions, study findsPresymptomatic and asymptomatic COVID-19 cases contributed at least 50% of transmissions during New York City's first COVID surge, according to a study published yesterday in Proceedings of the National Academy of Sciences.The researchers applied a stochastic epidemiologic model that integrated daily changes in testing capacity to New York City's case and serologic data from Mar 1 to Jun 1, 2020, and Mar 8 to Apr 19, 2020, respectively.
While asymptomatic transmission rates are still unknown, the researchers report that asymptomatic and symptomatic cases had reproduction rates of at least 3 in every reasonable simulation—above the estimated 2 to 3 rate reported in many