Serological studies to quantify SARS-CoV-2 population infection risk in Singapore, Hong Kong and Thailand

We propose a prospective serological study to investigate the incidence of SARS-CoV-2 infection in the general population in three Asian settings: Singapore, Hong Kong and Thailand. The study will aim to measure the age-specific seroprevalence and incidence of SARS-CoV-2 infection at 3 time points, each 6 months apart. Age-specific incidence estimates will be applied to the census population to obtain numbers of infections in the population at each time point. These estimates will be compared with external data on COVID-19 hospitalisations and deaths in each setting, to calculate age-specific infection-hospitalisation and infection-fatality ratios. SARS-CoV-2 antibody kinetics will be defined by studying changes in antibody titres over time. Risk factors for infection will be studied by comparing SARS-CoV-2 seroconverters and non-seroconverters with respect to epidemiological exposures. This study will provide crucial information regarding population exposure and SARS-CoV-2 transmission dynamics, and will provide a complete picture of the relationship between clinically apparent and asymptomatic infections.