In the Journals: Three Ways to Protect Babies Against RSV

Every year in the United States, respiratory syncytial virus (RSV) makes many children ill, causing:

• 1.5 million outpatient visits
• 500,000 emergency department visits
• 60,000 to 80,000 hospitalizations
• 100 to 300 deaths

Indeed, RSV causes more children to be hospitalized than any other virus. Most hospitalizations occur in children less than 3 months old — too young to be prevented by an active vaccine. For that reason, two passive vaccine approaches have been advanced. In August 2023, the CDC recommended nirsevimab (Beyfortus™) — a long-acting monoclonal antibody directed against an RSV surface protein — for all babies less than 8 months of age to be given before the winter RSV season. Nirsevimab was about 80% effective at preventing severe RSV disease.

Also in August 2023, the FDA licensed a maternal RSV vaccine to be given between 32 and 36 weeks gestation. In a clinical trial, RSV-specific antibodies that were passively transferred to the baby were about 70% effective at preventing severe RSV disease for the first six months of life.

There is, however, another way to prevent RSV that is inexpensive and safe — breastfeeding. Researchers in Ireland recently reviewed 19 studies that assessed the impact of breastfeeding in 16,787 infants living in 31 countries (Minerva GM, Purtill H, Dunne CP, Philip RK. Impact of breastfeeding on the incidence and severity of respiratory syncytial Virus (RSV)-associated acute lower respiratory infections in infants: a systematic review highlighting the global relevance of primary prevention. BMJ Glob Health. 2023 Feb;8(2):e009693). They found that exclusive breastfeeding for four to six months decreased the incidence of outpatient visits, emergency department visits, hospitalizations, and intensive care unit admissions.

It would be interesting to do a head-to-head-to-head trial comparing nirsevimab to maternal immunization to breastfeeding. It is entirely possible that breastfeeding would be equally protective and wouldn’t be burdened with the cost issues of nirsevimab or some of the safety concerns surrounding the maternal RSV vaccine.