Infants receiving nirsevimab fare better against RSV compared to those with maternal vaccination

 Respiratory syncytial virus (RSV) is a common virus that affects the nose, throat, and lungs. For most healthy adults and children, it causes only mild, cold-like symptoms and goes away on its own. Infants under 6 months of age, however, can become much sicker and might need special medical care. It is one of the leading reasons for infants getting hospitalized.

There are two common ways to protect babies against RSV: vaccinating pregnant mothers with RSVpreF, and giving infants a direct antibody injection. For a long time, medical practitioners were unsure which option worked better. A team of researchers from France may have found an antidote to this dilemma.

In a recent study of 42,560 infants, researchers found that during the first RSV season in France, those who received nirsevimab—a long-acting injection used for passive immunization against respiratory syncytial virus (RSV)—were less likely to develop complications and require hospital care. Compared with infants whose mothers received the RSV vaccine during pregnancy, their risk was about 26% lower.

The findings are published in JAMA.

RSV in the winter air

RSV infections typically begin to rise in the fall and spread at full swing during the winter months. The virus is highly contagious and can spread by breathing in air containing droplets released when an infected person coughs or sneezes, or by touching a contaminated surface and then touching one's eyes, nose, or mouth.

In infants, because their immune systems are still developing, RSV infection can be more severe than in adults. The virus often targets the lungs, causing acute bronchiolitis, a condition where the tiny airways become inflamed and narrowed, making breathing much harder. Some infants may require supplemental oxygen, and in severe cases, care in a pediatric intensive care unit (PICU) may be necessary for close monitoring.

Better of the two

Research shows that immunization can help reduce the severity of RSV infections. The two main ways of providing protection work in very different ways, where one depends on the mother's body to pass antibodies to the baby, while the other delivers protection directly to the infant. However, there was a lack of studies that compared their effectiveness head-to-head.

The researchers of this study, the team, accessed the nationwide database from the French National Health Data System and collected records for nearly every baby born in mainland France between September and December 2024.

They tracked 42,560 infants, comprising two groups of 21,280 each. One group of infants included those whose mothers received the RSV vaccine during the eighth month of pregnancy, and the other group of infants who received a nirsevimab injection at the hospital after birth.

The study found that infants who received nirsevimab were over one-quarter less likely to be hospitalized due to RSV compared with babies whose mothers got the RSV vaccine during pregnancy. The former group is 42 and 43% less likely to require care in the pediatric intensive care unit (PICU) and mechanical ventilation.

The researchers found that while the maternal vaccine offered a slight edge in the first week of life, nirsevimab grew stronger with time, providing consistent protection for nearly four months.

Studying a larger, more diverse population is needed to confirm whether these trends hold more broadly, as the results could help guide national immunization strategies for protecting infants against RSV.

Publication details

Marie-Joelle Jabagi et al, Nirsevimab vs. RSVpreF Vaccine for Respiratory Syncytial Virus–Related Hospitalization in Newborns, JAMA (2025). DOI: 10.1001/jama.2025.24082

https://medicalxpress.com/news/2026-01-infants-nirsevimab-fare-rsv-maternal.html