RSV on the rise, but antibody shots and vaccines can protect babies

RSV on the rise – antibody shots and vaccines can protect babies

Lauren J. by young Edited by Tanya Lewis

Winter illnesses are plaguing America, a mutant influenza variant is sending droves of people to hospitals, 32 children have died from the flu so far this season, whooping cough has killed more than a dozen, and now respiratory syncytial virus (RSV) is on the rise.

RSV season in the US typically peaks in January and February, with cases often stretching into March. The number of national emergency room visits and hospitalizations due to the virus among children ages four and younger has declined slightly, but overall increases are occurring in more than a dozen states, according to the latest report from the Centers for Disease Control and Prevention, dated Jan. 16. Overall RSV activity is increasing in many areas; National Wastewater Monitoring Sites—which can predict future waves of infection in communities—have detected the virus in high concentrations.

“RSV is a really big problem, but we have really effective interventions,” says Yvonne Maldonado, a pediatrician at Stanford University School of Medicine.

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New studies show that both RSV vaccination during pregnancy and doses of protective antibodies given to infants in the first eight months of life are highly effective in preventing severe disease in infants. That protection may last longer than one RSV season. But the CDC is currently reporting sub-optimal RSV vaccination coverage for children and adults — and experts worry that those rates will continue to decline given recent cutbacks in childhood vaccine recommendations overall. Additionally, unfounded skepticism about RSV vaccination by Health and Human Services Secretary Robert F. Kennedy, Jr. may set the stage for a more dangerous RSV season.

Almost everyone becomes infected with RSV at some point in their lives. For most healthy individuals, it causes a bad cough, runny nose, or fever. This virus can also cause serious illness long term complications In older adults. And the infection can be especially life-threatening for young children: The virus is the number one cause of hospitalization of infants in the U.S. — with the highest risk during the first two months of life. In infants, RSV can cause serious lung infection, or pneumonia, and, in extreme cases, death.

“RSV is a virus that causes the body to secrete a lot of mucus that can get stuck in the small airways of young children and cause a lot of breathing problems,” says Ruth Caron, MD, a pediatrician and director of the Johns Hopkins Vaccine Initiative. “children who are otherwise healthy In fact the need for ventilator support may be eliminated. This is really a serious disease.”

Fortunately, two very effective devices became available in the US in 2023 that protect newborns from RSV during the early months of life, who lack a fully developed immune system. The vaccine for pregnant people – which is recommended to be given between 32 and 36 weeks of gestation during RSV season – boosts antibodies to the virus that is transferred to the fetus through the placenta. These antibodies target a surface protein on the virus, preventing it from attaching to human cells.

If a pregnant person does not get the vaccine or is not eligible during RSV season, babies can receive protective antibodies directly through monoclonal antibody shots in the first months of life. These vaccines are not vaccines. A dose of one of the two available monoclonal shots, nirsevimab (Befortus) or clasrovimab (Enfloncia), is recommended for infants eight months and younger — and should be given just before RSV season to ensure protection continues during the virus’s most active months. The second dose may be given to older, higher-risk babies, such as those who were born prematurely.

“Infants who get either the vaccine or the monoclonal antibody may be protected from RSV for six months and potentially longer,” says Maldonado.

Both options are highly effective and safe, but recent studies suggest that monoclonal antibodies may have some additional benefits compared to vaccination.

A large recent study in France found that the antibody shot nirsevimab was associated with a lower risk of hospitalization and serious complications from RSV compared with the vaccine given in utero. After the first month of life, the difference became more pronounced in later follow-ups, says the study’s lead author, pharmacoepidemiologist Mary Joelle Jabbaghi. “This suggests that the duration and timing of protection may play an important role in real-world effectiveness, especially during the full RSV season,” she says.

One explanation for the results may be because nersevimab provides direct, immediate immunity and relatively uniform antibody levels to the infant. In contrast, protection from the vaccine depends on the timing of vaccination and how efficiently the antibodies transfer across the placenta, Jabaghi ​​says.

Another study published last week found that nersevimab RSV hospitalizations among infants in Spain drop by 86 percent for the first time During the 2023-2024 season. The data also show that protection continues into the next season in some infants.

However, experts emphasize that even though these recent studies show that nersevimab may provide greater and longer-lasting protection, the vaccine is still a very effective tool for preventing severe RSV for pregnant people. “I think all of these products are phenomenal,” Caron says. “If they are used appropriately, they can really have a huge impact on RSV hospitalizations.”

This impact is already being felt in the US: In the 2024-2025 season – the first season after both the vaccine and nersevimab are available – RSV hospitalization rates dropped by 43 percent in children ages zero to seven months. But experts fear that pace could slow under recent changes to the childhood vaccination program by the Trump administration. Recommendations for maternal RSV vaccine and monoclonal antibody dosage remain technically unchanged but with greater emphasis on high-risk infants. Karen worries the language may confuse some parents.

“If your child is completely healthy, you don’t think of that child as a high-risk child. If you’re reading this and it says ‘high-risk children only,’ that’s an incredible deterrent,” she says. “We really hope these products continue to be used so we can keep kids healthy.”

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