Maternal RSV vaccine cuts RSV hospitalizations in infants by 80% through six months

The earliest months of life are when babies are most vulnerable to serious RSV infection. In Australia, vaccination during pregnancy has now been linked to an 80.8% reduction in RSV-related hospitalizations through an infant’s first six months, according to the STREETON study from The Kids Research Institute Australia and nine hospitals across the country.

The researchers analyzed 1,012 infants hospitalized with acute respiratory illness. Maternal vaccination was 77.8% effective against hospitalization for RSV-related lower respiratory tract disease and 80.4% effective against severe forms of that disease. Among babies up to two months old, protection against lower respiratory tract disease reached 86.3%.

The result also speaks to how the vaccine fits into care. Protection remained consistently high whether the dose was given at different points in the recommended pregnancy window, beginning at 28 weeks of gestational age, or alongside other routine maternal vaccines. That supports its integration into standard prenatal care, according to Dr. Ushma Wadia, a clinician-scientist at the Wesfarmers Centre of Vaccines and Infectious Diseases, a pediatrician at Perth Children’s Hospital, and a clinical senior lecturer at the University of Western Australia’s Medical School.

So what changes in practice? For pregnant patients, primary-care doctors, obstetricians and midwives, the findings support using maternal RSV vaccination as part of routine pregnancy care to reduce the chance that a young baby will need hospital treatment for severe RSV. Australia introduced the vaccine through its National Immunisation Program in early 2025; the study is a real-world evaluation of that rollout, not a laboratory result.

The evidence still has boundaries. Researchers say they will continue testing effectiveness with larger sample sizes, including different infant subgroups, babies born outside RSV season, and protection beyond six months. The current findings show strong protection during the period studied, while those unanswered questions remain open.