HOW WILL DEMOGRAPHIC CHANGE AFFECT THE DISEASE BURDEN OF FUTURE EPIDEMICS?

Abstract

Intro: The burden of infectious diseases is influenced by the structure of the population at risk. Population ageing may have implications for the disease burden of future epidemics. Moreover, changing household structures induced by population ageing may influence the dynamics of disease transmission and burden of infections transmitted via close contact interactions. We aim to investigate the impact of demographic change on the disease transmission dynamics and future disease burden and illustrate this for COVID-19 and influenza-like illness (ILI). Methods: We simulate the Belgian population between 2020 and 2050 using an individual-based model with census data. The simulated population structures were used as input for an infectious disease model that distinguishes between exposure to infection in the household versus exposure in the community at large. We mimicked outbreaks of COVID-19 and ILI of varying total final size. Findings: The simulated population ages between 2020 and 2050, which also affects household size and composition. As the proportion of elderly people in the population increases, the overall attack rate slightly decreases because older age groups have fewer contacts and are therefore less likely to incur and transmit infections. Despite the lower per-person attack rate, the estimated disease burden increases as morbidity and mortality increases with the age at infection. Conclusion: The demographic changes induced by population ageing have an impact on the burden of future outbreaks of COVID-19 and ILI in Belgium. The shifting age distribution implies that the elderly, a population group with increased morbidity and mortality in case of infection, make up an increasing proportion of the total population. Population ageing also leads to an increasing proportion of single-person households and collective households (e.g. nursing homes) in the population. Since the household attack rate varies by household size and composition, the living arrangements of the elderly population influences the disease burden of future epidemics to some extent.