Estimating the basic reproduction number of measles in low-and middle-income settings using 172 seroprevalence studies: A modelling approach

The basic reproduction number, R0, is an epidemiological measure to describe the transmissibility of infectious diseases and evaluate the potential effect of interventions. Measles R0 has historically been considered to be between 12-18, with contextual factors contributing to its heterogeneity, but has rarely been estimated using data across multiple countries. Our study aims to estimate measles R0 in low- and middle-income countries using a standardised database of population-based serosurveys. We fitted an age-structured compartmental model of measles transmission dynamics and vaccination (DynaMICE) to the age-specific seroprevalence data extracted from a recent systematic review. Using Markov Chain Monte Carlo, we estimated setting-specific posterior distributions of R0 in 172 studies with unique survey years and locations from 57 countries. Bootstrapped samples of R0 estimates were pooled by study characteristics, including survey period, geography, and overall bias in sampling, measurement, and reporting results. Measles R0 estimates varied substantially across serostudies, ranging from 0.93 (95% credible interval (CrI): 0.70-1.00) to 147 (95% CrI: 76.5-208), with fewer than 13% of studies having median R0 values in the range of 12-18. Pooled R0 estimates showed smaller medians and variation in serostudies conducted after 2000 or including the adult population, while no distinguishable variation was identified across the World Health Organization regions. Our revised estimates demonstrated the wide range of measles R0 across low- and middle-income settings and highlighted the importance of considering the heterogeneity in measles transmissibility when modelling epidemics and planning interventions and vaccination strategies.