Trends in endemic of respiratory syncytial virus infection during COVID-19 pandemic and difficulty in obtaining optimal timing of palivizumab prophylaxis

Objective: The coronavirus disease (COVID-19) pandemic has affected the epidemiology of respiratory syncytial virus (RSV) infection. This study assessed whether or not palivizumab prophylaxis was appropriate during the COVID-19 pandemic.

Methods: This prospective study included children <24 months old who were hospitalized for RSV infection between April 2019 and March 2023. We compared the clinical characteristics of inpatients with RSV infection, with and without palivizumab prophylaxis.

Results: During the investigation period, 2,133 children <24 months old were hospitalized for RSV infection. The hospitalization rate of RSV infection in children receiving palivizumab prophylaxis (0.7%) was significantly lower than that in children without the prophylaxis (3.1%, P <0.001), indicating that the timing of prophylaxis was roughly appropriate in preventing hospitalization for RSV infection. In contrast, palivizumab prophylaxis was performed during the non-endemic period of RSV infection due to changes in RSV infection endemics due to the impact of the COVID-19 pandemic.

Conclusion: Palivizumab is useful in preventing hospitalization for RSV infection in children with a high risk of developing severe respiratory tract infections. However, since the RSV infection endemics varies not only during the occurrence of an emerging infectious disease, such as COVID-19, but also from year to year, a system that can quickly recognized the endemics is needed to avoid the inappropriate use of palivizumab. Furthermore, it is also necessary to actively promote maternal RSV vaccination to prevent severe RSV infection in all infants and young children.