A new study reveals that U.S. hospitals saw a significant drop in infant admissions for respiratory syncytial virus, or RSV, following the widespread use of two preventive measures. These include - a maternal vaccine administered during pregnancy, a monoclonal antibody treatment given directly to newborns. Both tools became broadly available during the 2024–2025 RSV season, marking a major shift in public health protection for babies.
Table of Contents:
- Lower hospitalization rates confirmed in RSV surveillance systems
- Greatest impact seen in youngest infants
- How the preventive tools work
- Outlook and accessibility concerns
Lower hospitalization rates confirmed in RSV surveillance systems
Data from two national surveillance systems were used to assess the impact of the new interventions. The RSV-Associated Hospitalization Surveillance Network, which includes roughly 300 hospitals in 13 states, showed that RSV hospitalization rates for infants up to 7 months old dropped from 15 per 1,000 to 8.5 per 1,000, a 43 percent decrease compared to seasons before the COVID-19 pandemic. These pre-pandemic years were the last ones considered “typical” for RSV.
The second source, the New Vaccine Surveillance Network, which includes data from pediatric hospitals in seven large U.S. cities, confirmed this trend. Hospitalization rates in infants under 7 months dropped from 15 to 11 per 1,000, reflecting a 28 percent decrease between 2018–2020 and the latest season.
Greatest impact seen in youngest infants
The most significant declines were seen in babies under 2 months old, who are especially vulnerable to severe RSV lung infections. In this age group:
- The hospitalization rate fell by 52 percent in the RSV-Associated Hospitalization Surveillance Network
- A 45 percent drop was observed in the New Vaccine Surveillance Network
According to dr Kawsar Talaat of the Johns Hopkins University Bloomberg School of Public Health, who was not involved in the study, RSV is the leading cause of infant hospitalization in the U.S. She emphasized that the virus is especially dangerous due to the small size of infants’ airways, which can become blocked by mucus and inflammation. This makes breathing extremely difficult for them.
How the preventive tools work
The U.S. Centers for Disease Control and Prevention currently recommends the use of either of the two tools:
- Maternal vaccine: A single dose administered during a specific window in the third trimester of pregnancy. The vaccine allows antibodies to transfer to the fetus, offering protection for up to six months after birth.
- Monoclonal antibody treatment (nirsewimab): This lab-produced antibody is given to babies born during or entering RSV season and provides at least five months of protection.
Both tools block a protein that RSV uses to infect lung cells, stopping the virus from taking hold.
Outlook and accessibility concerns
The drop in RSV-related hospitalizations marks a major milestone in infant health in the United States. Experts suggest that widespread use of these tools could make RSV-related hospital stays increasingly rare. However, many low-income countries still lack access to such treatments. Dr Talaat underlined the importance of ensuring availability of these protective measures worldwide, especially in areas where child mortality from RSV remains high due to limited healthcare access.
This latest data signals progress but also highlights the need for broader global implementation to protect the most vulnerable infants.
Source: Science News