May 26, 2024

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Pfizer’s RSV Vaccine Shows Promise in Expanding Protection for Adults

Pfizer’s RSV Vaccine Shows Promise in Expanding Protection for Adults

Pfizer’s RSV Vaccine Shows Promise in Expanding Protection for Adults: A Look at the Data

On April 9th, 2024, Pfizer, a leading pharmaceutical company, announced positive results from their late-stage clinical trials for a respiratory syncytial virus (RSV) vaccine.

This news brings hope for broader protection against RSV, a common respiratory illness that can be particularly severe in vulnerable populations.

While previous studies focused on adults 60 and older, this latest development suggests the vaccine’s efficacy might extend to younger adults with underlying health conditions.

Pfizer's RSV Vaccine Shows Promise in Expanding Protection for Adults

The Burden of RSV

RSV is a highly contagious virus that affects people of all ages, but it can be particularly dangerous for infants, older adults, and individuals with chronic health conditions. It causes infections of the upper and lower respiratory tract, leading to symptoms like cough, congestion, fever, and wheezing.

For otherwise healthy adults, RSV typically resolves on its own. However, in high-risk groups, RSV can progress to lower respiratory tract illness (LRTI), including pneumonia and bronchiolitis. These complications can lead to hospitalization and even death.

The Centers for Disease Control and Prevention (CDC) estimates that annually in the United States alone, RSV leads to:

  • 14,000 to 17,000 hospitalizations among adults aged 65 years or older
  • 100,000 to 500,000 visits to healthcare providers for bronchiolitis in infants under one year of age
  • 1-4% of these infants requiring hospitalization

Existing RSV Vaccine Landscape

Currently, no widely available vaccine exists to prevent RSV infection. However, several promising candidates are undergoing development. One such candidate is Pfizer’s RSVpreF vaccine (also known as ABRYSVO).

Published research in the New England Journal of Medicine (NEJM) detailed the results of a Phase 3 clinical trial for RSVpreF in adults 60 years and older [1]. The study demonstrated significant efficacy against RSV-associated LRTI, with a rate of 85.7% for illness with at least three symptoms and 66.7% for illness with at least two symptoms.

Expanding Protection: The Latest Data

Pfizer’s recent announcement highlights positive results from the MONeT study, another Phase 3 clinical trial investigating RSVpreF. This study specifically focused on adults aged 18 to 59 who are considered at increased risk for severe RSV disease due to underlying health conditions.

While detailed efficacy data from the MONeT study haven’t been published yet, Pfizer’s press release states that the vaccine met its primary endpoints. The participants demonstrated immune responses non-inferior to those observed in the previous study with adults 60 and older [2]. This suggests that RSVpreF might offer similar protection to younger adults with risk factors.

Significance for Public Health

The potential inclusion of younger adults in the target population for RSV vaccination could significantly impact public health. Here’s why:

  • Broader Protection: By offering RSV protection to a wider age group, the vaccine could help reduce the overall burden of the disease on healthcare systems.
  • Reduced Hospitalizations: Vaccination in high-risk younger adults would lead to fewer hospitalizations due to RSV complications.
  • Indirect Protection for Infants: Vaccinating younger adults, especially parents and caregivers, could create a protective cocoon around infants who are most vulnerable to RSV. This strategy, known as maternal immunization, has shown promise in reducing RSV infections in newborns [3].

Future Considerations

While the initial data from the MONeT study is encouraging, further research is needed. The full efficacy data, including the vaccine’s effectiveness against different RSV strains and its long-term durability, needs to be published and reviewed by regulatory bodies. Additionally, further studies are required to determine the optimal timing and dosing schedule for vaccination in younger adults with various health conditions.


Pfizer’s RSV vaccine holds significant promise for protecting a broader population against this potentially serious respiratory illness.

The inclusion of younger adults with underlying health conditions could significantly contribute to reducing the burden of RSV on individuals and healthcare systems.

Continued research and regulatory approvals are crucial steps towards making this potentially life-saving vaccine widely available.

Pfizer’s RSV Vaccine Shows Promise in Expanding Protection for Adults


  • [1] N Engl J Med. 2022;387(21):2016-2026. doi: 10.1056/NEJMoa2213836. Efficacy and Safety of a Bivalent RSV Prefusion F Vaccine in Older Adults. Openshaw PJ, Anderson EC, Kim YH, et al
  • [2] Pfizer Announces Positive Top-Line Results from Phase 3 Study of ABRYSVO® in Adults Aged 18 to 5

(source:internet, reference only)

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Important Note: The information provided is for informational purposes only and should not be considered as medical advice.