Relative timing of respiratory syncytial virus epidemics in summer 2021 across the United States was similar to a typical winter season

We used a validated proxy of respiratory syncytial virus (RSV) activity in the United States (Google search data) to evaluate the onsets of RSV epidemics in 2021 and 2016-2019. Despite the unusual out-of-season summer timing, the relative timing of RSV epidemics between states in 2021 shared a similar spatial pattern with typical winter RSV seasons. Our results suggest that the onset of RSV epidemics in Florida can serve as a baseline to adjust the initiation of prophylaxis administration and clinical trials in other states regardless of the seasonality of RSV epidemics.

Automated summary

This study used Google search data as a validated proxy to evaluate the onset of RSV epidemics in 2021 and 2016-2019. Despite the unusual occurrence of RSV epidemics in summer, the relative timing of RSV epidemics between states in 2021 showed similarities with typical winter seasons. The findings suggest that the onset of RSV epidemics in Florida can be used as a baseline for adjusting prophylaxis administration and clinical trial initiation in other states, regardless of the seasonality of RSV epidemics.