A maternal vaccine that creates a shield for the unborn
In short: RSV is a common virus that usually causes mild colds, but for infants and older adults, it can be life-threatening. A new vaccine offers a unique solution: by vaccinating pregnant people, they can pass protective antibodies through the placenta, shielding their babies from birth.
Respiratory syncytial virus (RSV) is a major respiratory pathogen that typically peaks between November and February. While most infections are mild, it can cause severe bronchiolitis in infants—a lung infection causing inflammation in small airways—and pneumonia in older adults. Before the introduction of vaccines, RSV caused approximately 30,000 hospitalizations of children under 5 annually in the UK, with 20 to 30 infant deaths. In adults over 75, it led to roughly 9,000 annual hospitalizations, often triggering flare-ups of chronic conditions like COPD.
To generate antibodies, the maternal vaccination approach strengthens the immunity of the mother. These antibodies cross the placenta, providing the newborn with protection during the first six months of life, which is when they are most vulnerable. Data from the 2025-26 season in England showed a 50% reduction in RSV-related intensive care admissions for infants under 6 months following the rollout. In the US, studies of the 2023-2024 season showed that vaccines like RSVPreF3+AS01 and RSVpreF were approximately 81.8% to 85% effective against RSV-related hospitalization and death in adults aged 65 and older.
Vaccination is currently recommended for pregnant individuals from 28 weeks gestation to protect the baby. For older adults, a single dose is typically sufficient for several years. While rare, some older adults may experience Guillain-Barré syndrome, a condition affecting the nerves, but health authorities emphasize that the vaccine is significantly safer than the risk of a serious RSV infection. The vaccine is administered as an injection into the upper arm and is available year-round, unlike the seasonal flu shot.
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Sources
- Summary by Intellect · source: RSV vaccine
- Also: What is RSV and who is eligible for the vaccine? – UK Health Security Agency
- Also: Respiratory syncytial virus vaccine
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