Measures to reduce the spread of COVID-19 through non-pharmaceutical interventions (NPIs) such as mask wearing and social distancing also have greatly reduced incidence of many other diseases, including influenza and respiratory syncytial virus (RSV). Current reductions in these common respiratory infections, however, may merely postpone the incidence of future outbreaks, according to a study published in the Proceedings of the National Academy of Sciences.

The study authors found that even relatively short periods of NPI measures could lead to large future outbreaks of RSV, an endemic viral infection in the United States and a leading cause of lower respiratory-tract infections in young infants.

The researchers used an epidemiological model to examine the possible impact of NPIs on future RSV outbreaks in the United States and Mexico. These outbreaks were often delayed following the end of the NPI period, with peak cases projected to occur in many locations in winter 2021-22.

The authors also considered the implications of COVID-19 NPIs for seasonal influenza outbreaks and found results qualitatively similar to RSV. The dynamics of influenza are much harder to project due to viral evolution, however, which drives uncertainty over future circulating strains and the efficacy of available vaccines.