Case 26-2025: 11-Year-Old Girl Chest Pain Lesions
- what: The first FDA-approved vaccines to prevent respiratory syncytial virus (RSV), a common and perhaps serious respiratory illness.
- When: FDA approval announced May 3, 2023, with initial rollout beginning Fall 2023.
- Why it Matters: RSV causes critically importent morbidity and mortality, notably in vulnerable populations.
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RSV Vaccine Breakthrough: Protecting Infants and Older Adults
Understanding RSV: A Threat Across the Lifespan
respiratory Syncytial Virus (RSV) is a common respiratory virus that usually causes mild,cold-like symptoms. However, for infants, young children, and older adults, RSV can lead to severe illness, including bronchiolitis and pneumonia. Before the advent of these vaccines, RSV was responsible for an estimated 60,000-160,000 hospitalizations and 6,000-10,000 deaths annually among older adults in the United States.
The virus spreads through respiratory droplets produced when an infected person coughs or sneezes. Symptoms typically appear 4-6 days after infection and include runny nose, decreased appetite, cough, sneezing, fever, and wheezing. While most people recover within a week or two, severe cases can require hospitalization and supportive care.
The Vaccines: Arexvy and Abrysvo – How They Work
The newly approved vaccines represent a significant leap forward in RSV prevention. These vaccines utilize different technologies to stimulate an immune response against the RSV fusion (F) protein, which is crucial for the virus to enter cells.
Arexvy, manufactured by GSK, is a recombinant subunit vaccine, meaning it contains a purified piece of the RSV F protein. Abrysvo, developed by Pfizer, employs a bivalent mRNA vaccine, delivering genetic instructions to cells to produce the F protein.
Clinical trials have demonstrated the efficacy of both vaccines. Data published in the New England Journal of Medicine in September 2025, showed that Abrysvo, when administered to pregnant individuals, resulted in a substantial reduction in RSV-related hospitalizations and severe illness in their infants during the first six months of life.Specifically, maternal vaccination led to a 77.3% efficacy against medically attended RSV infection in infants.
For older adults, both vaccines showed promising results. Arexvy demonstrated approximately 82.6% efficacy against RSV-associated lower respiratory tract disease (LRTD) in adults aged 60 years and older, while Abrysvo showed around 66.3% efficacy in the same age group. The long-term data from 2025 continues to support these initial findings, with minimal waning of protection observed over a two-year period.
Clinical Trial Data: A Closer Look
| Vaccine | Target Population | Efficacy (vs. RSV-LRTD) | Key Findings (as of Sept 2025) |
|---|---|---|---|
| Arexvy (GSK) | Adults ≥60 years | 82.6% | Sustained efficacy over two years; minimal waning of protection. |
| Abrysvo (Pfizer) | Adults ≥60 years | 66.3% | Demonstrated efficacy in preventing severe RSV disease
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