Age-dependent effects in the transmission and control of COVID-19 epidemics

Nicholas G Davies; Petra Klepac; Yang Liu; Kiesha Prem; Mark Jit; Rosalind M Eggo

. (b) Susceptibility by age for the three hypotheses. Age-specific values were estimated for hypothesis 2 and all ages had equal susceptibility for hypothesis 1 and 3. Susceptibility is measured as the probability of infection on contact with an infectious person. (c) Clinical fraction ( y i ) by age for the 3 hypotheses. Age-specific values were estimated for hypothesis 3 and all ages were equal for hypothesis 1 and 2. (d) Fitted contact multipliers for holiday and restricted periods for each hypothesis showed an increase in non-school contacts beginning on January 12th (start of Lunar New Year) and a decrease in contacts following restrictions on January 23rd. (e) Estimated R 0 values under each hypothesis. The red barplot shows the inferred window of spillover of infection. (f) Incident reported cases (black), and modelled incidence of clinical cases for the three hypotheses as fitted to the cases reported by China Centers for Disease Control 1 with onset on or before February 1st, 2020. Line marks mean and shaded window is the 95% highest density interval (HDI). (g) Age distribution of cases by onset date as fitted to the age distributions reported by Li et al. 26 Data are shown in the hollow bars, and model predictions in filled bars, where the dot marks the mean posterior estimate. (h) Inferred distribution of subclinical cases by age under each hypothesis. Credible intervals on modelled values show the 95% HDIs; credible intervals on data for panels d-f show 95% HDIs for the proportion of cases in each age group.