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

Model parameters were based on current data for SARS-CoV-2 natural history and epidemiology, or through model fitting to the China outbreak data [4] (Supplementary Section 2 and Table S1 ). Namely, the overall infectious contact rate, age-specific biological susceptibility profile, and age-specific mortality rate were assumed as those in China [4] . The population size, demographic structure, and life expectancy in countries and territories with a population of ≥1 million, as of 2020, were extracted from the United Nations World Population Prospects database [14] . Model parameters, definitions, values, and justifications are in Supplementary Section 2 and Tables S1 and S2. Indices for mortality, infection severity, and susceptibility were derived by weighting each of these factors in each age group by the fraction of the population in that age group, and then summing the contributions of all ages.