The time scale of asymptomatic transmission affects estimates of epidemic potential in the COVID-19 outbreak

Sang Woo Park; Daniel M Cornforth; Jonathan Dushoff; Joshua S Weitz

If asymptomatic infections are more persistent than symptomatic ones, the mean generation interval for COVID-19 could be longer than estimated from symptomatic cases alone -possibly causing R 0 to be underestimated ( Figure 1B) . However, if asymptomatic cases tend to resolve quickly, then current estimates of R 0 may be over-estimates of the underlying strength ( Figure 1B) , and asymptomatic cases may be driving a larger fraction of secondary cases than we would expect without accounting for their differences ( Figure 1A) . The importance of these effects depends on the relative infectiousness of asymptomatic transmission as well as the proportion of incident cases that are asymptomatic (and therefore the intrinsic proportion of asymptomatic transmission z). The biases in the estimates of R 0 will necessarily bias estimates of the amount of intervention required to control the epidemic.