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, indicating that both vaccine products demonstrated high efficacy in older adults during the first RSV season following vaccination. The efficacy findings from phase 3 clinical trials of a single dose of the GSK or Pfizer RSV vaccine in RSV season 1 in older adults are summarized in the 2023 Advisory Committee on Immunization Practices (ACIP) recommendations for the use of RSV vaccines in older adults 1.
- The GSK RSV vaccine demonstrated an efficacy of 82.6% (96.95% CI: 57.9,94.1) in preventing 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) in preventing RSV-associated LRTD with ≥2 symptoms in adults aged ≥60 years 1. The similar efficacy profiles of both vaccines give clinicians flexibility in product selection based on availability and patient factors. 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. This robust immune response explains the substantial reduction in LRTD cases observed in the clinical trials. When presenting this information to medical residents, it's essential to note that while both vaccines show high efficacy in the first season, ongoing studies are evaluating the duration of protection and whether booster doses might be needed in subsequent seasons, as reported in a position paper from the Portuguese Society of Pulmonology 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.