[1] Univ Hong Kong, Li Ka Shing Fac Med, WHO Collaborating Ctr Infect Dis Epidemiol & Cont, Sch Publ Hlth,Pokfulam, 7 Sassoon Rd, Hong Kong, Peoples R China
[2] Lab Data Discovery Hlth D24H, Hong Kong Sci Pk, Hong Kong, Peoples R China
[3] Publ Hlth England, Modelling & Econ Unit, 61 Colindale Ave, London NW9 5EQS, England
[4] London Sch Hyg & Trop Med, Dept Infect Dis Epidemiol, Keppel St, London WC1E 7HT, England