Characterizing key attributes of the epidemiology of COVID-19 in China: Model-based estimations

Houssein H Ayoub; Hiam Chemaitelly; Ghina R Mumtaz; Shaheen Seedat; Susanne F Awad; Monia Makhoul; Laith J Abu-Raddad

The model was parameterized using current data on COVID-19 natural history and epidemiology. The duration of latent infection was set at 3.69 days based on an existing estimate [12] and based on a median incubation period across confirmed cases of 5.1 days [1] , adjusted for the observed viral load among infected persons following exposure [13] and reported infection transmission prior to onset of symptoms [14] . The age-stratified proportions of infected individuals that will eventually progress to develop mild, severe, or critical infections were based on the observed distribution of cases across these infection stages in China [3, 15, 16] . The duration of infectiousness was assumed to last for 3.48 days based on an existing estimate [12] and based on the observed time to recovery in persons with mild infection [3, 12] and the observed viral load among infected persons [13, 14] . Individuals with severe (or critical) infections develop severe (or critical) disease over a period of 28 days prior to recovery, as informed by the observed duration from onset of severe (or critical) disease to recovery [3] . Individuals with critical disease had the additional risk of disease mortality [17] . The disease mortality rate was fitted factoring the observed crude case fatality rate in each age group in China as of February 11, 2020 [2, 17] .