Impact of the COVID-19 pandemic on RSV epidemiology in Fukushima, Japan.

BACKGROUND

The COVID-19 pandemic that started in 2020 led to a significant reduction of many respiratory tract infections, including respiratory syncytial virus (RSV) infection.

METHODS

With the cooperation of all 16 pediatric inpatient facilities in Fukushima Prefecture, we actively investigated the total numbers of RSV hospitalizations and severe lower respiratory tract infections (LRTIs) requiring respiratory support during a 10-year period from 2014 to 2023. In addition, the number of sentinel RSV reports was obtained. We compared the disease burden of RSV infection between the period of 2014 and 2019 (defined as pre-pandemic) and that of 2021 to 2023 (defined as post-pandemic).

RESULTS

The annual number of sentinel RSV reports per 10,000 children aged <5 years after the pandemic increased to 611 from 445 compared to the pre-pandemic period. In contrast, the number of RSV-related hospitalizations decreased from 175 to 104, and the number of severe RSV-related LRTI cases decreased from 59 to 43. Analysis of sentinel reports and hospitalization numbers by age group showed a higher hospitalization rate in children aged <1 year compared to those aged ≥1 year. The age distribution of sentinel RSV reports was higher post-pandemic than pre-pandemic.

CONCLUSION

Although the number of sentinel RSV reports increased after the pandemic, the number of RSV cases requiring hospitalization decreased compared to before the pandemic due mainly to an increase in the age of the infected children. This indicates the importance of preventing initial infection in children aged <1 year.