Age could be driving variable SARS-CoV-2 epidemic trajectories worldwide

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

The model stratified the population into compartments according to age (0-9, 10-19, …, ≥80 years), infection status (uninfected, infected), infection stage (mild, severe, critical), and disease stage (severe, critical), using a system of coupled nonlinear differential equations (Supplementary Section 1). Susceptible individuals in each age group were assumed at risk of acquiring the infection at a hazard rate that varies based on the age-specific susceptibility to the infection (Supplementary Figure S1 ), the infectious contact rate per day, and the transmission mixing matrix between the different age groups (Supplementary Section 1). Following a latency period of 3.69 days [15] [16] [17] [18] , infected individuals develop mild, severe, or critical infection, as informed by the observed age-specific distribution of cases across these infection stages in China [8] [9] [10] . The duration of infectiousness was assumed to last for 3.48 days [8, 15, 17, 18] after which individuals with mild infection recover, while those with severe and critical infection develop, respectively, severe and critical disease over a period of 28 days [8] prior to recovery.