Mammarenavirus Infection Linked to Meningoencephalitis Case
- Food and Drug Management (FDA) approved Arexvy, a respiratory syncytial virus (RSV) vaccine, for adults aged 60 years and older on May 3, 2023.
- When: Approvals occurred in May and August 2023, with clinical trials preceding these dates.
- Why it Matters: RSV is a common respiratory virus that can cause severe illness, especially in older adults and infants.
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RSV Vaccine Approved for Older Adults: A Breakthrough in Respiratory protection
Table of Contents
Understanding RSV and Why It’s a Threat
Respiratory Syncytial Virus (RSV) is a highly contagious virus that infects the lungs and respiratory tract. While ofen causing mild, cold-like symptoms, RSV can lead to serious complications, particularly in vulnerable populations - infants, young children, and older adults. Before the growth of these vaccines, RSV was responsible for an estimated 60,000-160,000 hospitalizations and 6,000-10,000 deaths annually among adults 65 years and older in the United States.
The virus spreads through close contact with infected individuals, via respiratory droplets produced during coughing or sneezing. Symptoms typically appear 4-6 days after infection and can include a runny nose, decreased appetite, cough, sneezing, fever, and wheezing. In severe cases, RSV can lead to bronchiolitis (inflammation of the small airways in the lungs) and pneumonia.
The Breakthrough: Arexvy and Abrysvo – How They Work
The FDA’s approval of Arexvy (GSK) on May 3, 2023, and Abrysvo (Pfizer) on August 21, 2023, represents a significant advancement in preventing RSV-related illness. Both vaccines utilize different technologies to stimulate an immune response.
Arexvy is a recombinant subunit vaccine containing a stabilized prefusion F protein. This protein is found on the surface of the RSV virus and is crucial for the virus to enter cells. By presenting this protein to the immune system, the vaccine prompts the body to produce antibodies that can neutralize the virus. Clinical trial data, published in the new England Journal of Medicine (Volume 393, Issue 19) on November 13, 2025, demonstrated approximately 82.6% efficacy in preventing RSV-associated lower respiratory tract disease (LRTD) in adults 60 years and older.
Abrysvo also uses the prefusion F protein, but employs a different manufacturing process. Importantly, Abrysvo also received approval for use in pregnant people during the third trimester of pregnancy to protect their babies against RSV for several months after birth. This is a novel approach to infant RSV prevention.
Clinical Trial Results: A Closer Look at the data
The efficacy of Arexvy was evaluated in a large, randomized, placebo-controlled clinical trial involving nearly 25,000 adults aged 60 years and older. The trial, conducted across multiple countries, showed a statistically significant reduction in RSV-associated LRTD among those who received the vaccine compared to those who received a placebo. Specifically, the vaccine demonstrated 82.6% efficacy against three or more symptoms of LRTD, and 94.1% efficacy against severe LRTD.
Data from the Abry