Hospitalisations due to respiratory syncytial virus (RSV) infections largely decreased after social distancing measures were introduced to control the COVID-19 pandemic. Lifting these measures resulted in out-of-season RSV activity, sometimes exceeding the incidence of hospitalisations observed in regular seasons.1–3 Declining immunity due to reduced exposure to the virus may contribute to this altered epidemiology.1,4,5 Bardsley and colleagues1 showed that the combination of laboratory, clinical, and syndromic data capture the impact of RSV activity, yet did not provide insight into the proposed decline in immunity.