Study: RSV pattern changed during COVID-19 pandemic (By: Stephanie Soucheray, MA)

JAMA Health Forum has posted a new research letter showing how the seasonal pattern of respiratory syncytial virus (RSV) changed during the COVID-19 pandemic, with interseasonal spikes occurring as soon as the summer of 2021.

The research looked at four RSV seasons and identified infections in children younger than 2 years who required hospitalization for RSV between July 2017 and November 2022 using the Pediatric Health Information System (PHIS).

Children at high risk for RSV are eligible for immunoprophylaxis administration during seasonal spikes, and the American Academy of Pediatrics (AAP) guidelines recommend these children receive RSV monoclonal antibodies.

Insurers typically cover RSV immunoprophylaxis annually (November-March) in accordance with RSV seasonality, so the authors of the study looked at RSV-related hospitalizations among high-risk children with RSV-immunoprophylaxis eligibility.

High risk was defined as having hemodynamically significant congenital heart disease, chronic lung disease of prematurity, or less than 29 weeks’ gestation, the authors said.

May 2021 brought first post-pandemic spike

A total of 109,185 RSV-related hospitalizations among 104,898 children (median age, 4.7 months; 45,931 girls [43.8%], 58,947 boys [56.2%]) were recorded, with seasonal spikes in 2017 and 2019 beginning in October.

In May of 2021, however, a spike in RSV hospitalizations was noted after lockdown measures put in place during the COVID-19 pandemic were lifted. The 2020 seasonal transmission dynamics of the virus were likely due to school closures and masking.

RSV season was continuous, with monthly hospitalizations larger than the interseasonal threshold.

Beginning in May and June of 2021, 579 hospitalizations per month were recorded.

“RSV season was continuous, with monthly hospitalizations larger than the interseasonal threshold. The 2021 to 2022 RSV season consisted of 45% of all hospitalizations over the study period,” the authors said. “The RSV surge was missed by the time insurance covered RSV immunoprophylaxis. Many high-risk children could not receive RSV immunoprophylaxis during peak months.”

Following recent Food and Drug Administration (FDA) approval of the first RSV vaccines, indicated for seniors, the Centers for Disease Control and Prevention (CDC) last week finalized a recommendation, which said people can get a single dose of the vaccine based on shared clinical decision-making.

In May the FDA’s vaccine advisory group also recommended a vaccine from Pfizer for use in pregnant women to protect newborns.

The Centers for Disease Control and Prevention (CDC) estimates that 58,000 to 80,000 children under age 5 are hospitalized with RSV each year and that 1 to 2 of every 100 children younger than 6 months old with RSV may need to be hospitalized.