• Posted May 6, 2025

RSV Antibody Treatment Effective For Babies

Newborns can be effectively protected against respiratory syncytial virus (RSV) infection through the use of nirsevimab, a monoclonal antibody treatment, researchers report.

Babies treated with nirsevimab had an 83% reduced risk of hospitalization due to RSV infection, researchers reported May 1 in The Lancet Child & Adolescent Health.

The antibody treatment also reduced the risk of intensive care admissions by 81% and instances of lower respiratory tract infections by 75% in children younger than 1 year old, results show.

Nirsevimab also was more effective in preventing RSV-related hospitalizations in infants older than 3 months (81%) compared to those 3 months or younger (76%), researchers report.

“Our findings indicate that the benefits of nirsevimab observed in clinical trials are also evident in real-world settings, effectively reducing the burden of RSV disease in infants and, consequently, health-care use,” concluded the team led by senior researcher Seyed Moghadas, a professor of computational epidemiology and vaccine science with York University in Ontario, Canada.

The U.S. Centers for Disease Control and Prevention (CDC)  recommends that all babies be protected from RSV by one of two methods. An expectant mother can pass on protection by getting an RSV vaccine while pregnant, or a newborn can be given antibody treatment to protect them against RSV.

To check the effectiveness of nirsevimab, researchers combined data from 27 studies conducted during the 2023-2024 RSV season across five countries — France, Italy Luxembourg, Spain and the United States.

Although the protection from the antibody treatment was high, researchers found that its effectiveness did vary by country.

The U.S. had higher effectiveness, with 93% of treated infants avoiding hospitalization, compared with 83% in Spain and 76% in France.

That might be because more babies who got the antibody treatment were at high risk of severe disease in the U.S., researchers said. The U.S. prioritized nirsevimab treatment for high-risk infants during the season under study, due to a limited supply of the antibody treatment.

“Our findings underscore the importance of infant immunization programs in alleviating the health and economic burden of RSV disease in the high-risk period following birth,” researchers concluded.

More information

The U.S. Centers for Disease Control and Prevention has more on immunizing babies against RSV.

SOURCE: The Lancet, news release, May 1, 2025