New Breakthrough RSV Drug Successfully Prevents Infant Hospitalizations

Doctors and parents are celebrating the significant advancements made in 2023 in the treatment of respiratory syncytial virus (RSV), a virus that annually sends up to 80,000 children under the age of five to the hospital in the U.S. This year, the U.S. Food and Drug Administration (FDA) approved two crucial methods to reduce the risk of RSV in young children: a vaccine for pregnant mothers that can protect newborns, and a drug treatment for babies under one year old.

A study published in the New England Journal of Medicine has provided encouraging real-world data on the effectiveness of the drug treatment called nirsevimab (brand name: Beyfortus). The study, funded by the drug’s manufacturers Sanofi and AstraZeneca, involved over 8,000 infants from France, Germany, and the U.K. who were one year old or younger and entering their first RSV season, which occurs from fall to spring. Nirsevimab, a monoclonal antibody, functions similarly to a vaccine by training a child’s immune system to recognize and defend against RSV. Half of the babies in the study received nirsevimab, while the other half received no treatment. The drug was found to be 83% effective in preventing hospitalization among those who received it and 75% effective in reducing severe RSV. These results were consistent regardless of the baby’s age, gestational age, or sex.

Dr. Saul Faust, a pediatrician at University Hospital Southampton and co-leader of the study, expressed his excitement about the ability to prevent over 80% of children who received the drug from being hospitalized.

The findings of the study support recommendations by the U.S. Centers for Disease Control and Prevention (CDC) that any baby under 8 months old should receive a single injection of nirsevimab before their first RSV season if the mother has not already been vaccinated against RSV. However, since the drug’s approval in July, AstraZeneca and Sanofi have struggled to meet the increasing demand. An AstraZeneca spokesperson acknowledged the issues with supply, stating that the demand for Beyfortus has exceeded any previous standards.

In October, the CDC alerted doctors about measures to restrict the supply of nirsevimab to babies at the highest risk of RSV complications, such as younger and lower weight babies, as well as those with underlying health conditions. The agency also recommended that high-risk babies, including premature infants and those with heart and lung conditions, continue to receive an existing RSV treatment called palivizumab (brand name: Synagis). This allows supplies of nirsevimab to be available for babies who do not qualify for palivizumab. While palivizumab is safe and effective, it requires monthly injections throughout the RSV season, so the hope was to take advantage of nirsevimab’s single-injection.

For families with babies who are not at particularly high risk of RSV complications, Dr. Rick Malley, a pediatrician at Harvard Medical School and Boston Children’s Hospital, suggests other ways to protect infants even if they cannot receive the shot. During the holidays, parents can ask visitors to avoid close contact with the baby if they have any symptoms of respiratory infections, such as a fever, cough, or runny nose. If visitors insist on interacting with the baby, touching the infant’s feet instead of their face can reduce the risk of transmitting any infections.

Another reassuring aspect is that RSV infections tend to peak earlier in the season, indicating that the highest risk may be over for this year. Nevertheless, the manufacturer of nirsevimab expects supplies to gradually increase in the coming months. An AstraZeneca spokesperson stated that approximately 230,000 additional doses will be made available in mid-January for this RSV season, following the previous announcement in November that 77,000 additional doses were being made available.