What is the efficacy of GSK (Respiratory Syncytial Virus vaccine) or Pfizer (Respiratory Syncytial Virus vaccine) in preventing RSV-associated LRTD in older adults?

From the Guidelines

The risk of RSV-associated lower respiratory tract disease (LRTD) was approximately 82.6% lower in patients receiving a single dose of the GSK RSV vaccine and 65.1% lower in patients receiving a single dose of the Pfizer RSV vaccine compared with those in the control groups, with both vaccine products demonstrating high levels of protection against RSV-associated LRTD in the first RSV season following vaccination, as reported in the 2025 study published in Pulmonology 1. The phase 3 clinical trials for both vaccines showed similar high levels of protection against RSV-associated LRTD in the first RSV season following vaccination.

• The GSK RSV vaccine demonstrated an efficacy of 82.6% (96.95% CI: 57.9,94.1) against RSV-associated LRTD in adults aged ≥60 years 1.
• The Pfizer RSV vaccine demonstrated an efficacy of 65.1% (95% CI: 35.9,82.0) against RSV-associated LRTD in adults aged ≥60 years 1. This substantial reduction in disease risk represents a significant clinical benefit for older adults, who are at increased risk for severe RSV disease. The vaccines work by stimulating the immune system to produce antibodies against the RSV F protein, which is essential for viral entry into host cells. When presenting this information to medical residents, it's essential to emphasize that these vaccines represent an important preventive tool for reducing the burden of RSV disease in the older adult population, particularly those with underlying conditions who may be at highest risk for complications, as updated by the Advisory Committee on Immunization Practices in 2024 1. Key points to consider include:
• The updated recommendations from the Advisory Committee on Immunization Practices, which now recommend a single dose of any Food and Drug Administration–approved RSV vaccine for all adults aged ≥75 years and for adults aged 60–74 years who are at increased risk for severe RSV disease 1.
• The importance of continued postlicensure monitoring to guide future recommendations and ensure the safe and effective use of RSV vaccines in older adults 1.

From the Research

Efficacy of RSV Vaccines in Older Adults

• The efficacy of RSV vaccines in preventing lower respiratory tract disease (LRTD) in older adults has been evaluated in several studies 2, 3, 4, 5, 6.
• A systematic review and meta-analysis found that prefusion anti-RSV vaccines are efficacious in preventing LTRI/LTRD and ARI/ARD cases, with a vaccine efficacy of 73% for LTRI/LTRD and 61% for ARI/ARD 3.
• Another study found that the pooled vaccine efficacy for prevention of LRTD was 81.38% (95% CI 70.94 to 88.06) during the first RSV season after vaccination, but decreased to 61.15% (95% CI 45.29 to 72.40) in the second season 4.
• A retrospective case-control study estimated the vaccine effectiveness of RSVpreF against RSV-related LRTD hospitalization or ED visit to be 91% (95% CI, 59%-98%) using strict controls and 90% (95% CI, 59%-97%) using broad controls 5.
• The Advisory Committee on Immunization Practices (ACIP) recommends that adults aged ≥60 years may receive a single dose of an RSV vaccine, using shared clinical decision-making, based on the moderate to high efficacy of RSV vaccines in preventing RSV-associated lower respiratory tract disease 6.

Comparison of GSK and Pfizer RSV Vaccines

• The available evidence does not provide a direct comparison of the efficacy of the GSK and Pfizer RSV vaccines in older adults.
• However, the studies suggest that both vaccines have demonstrated moderate to high efficacy in preventing RSV-associated lower respiratory tract disease in older adults 2, 3, 4, 5, 6.
• Further research is needed to determine the comparative efficacy of the two vaccine products for specific outcomes, such as RSV hospitalization and medically attended LRTD.