RSVpreF Vaccine Proves Highly Effective Against Severe RSV in Older Adults
A real-world study conducted within Kaiser Permanente Southern California has found that Pfizer’s RSVpreF vaccine (Abrysvo) is highly effective in preventing serious respiratory syncytial virus (RSV)–related illness among adults aged 60 years and older. The retrospective analysis, spanning from November 24, 2023, to April 9, 2024, evaluated vaccine performance during its first respiratory virus season of use and offers compelling evidence for its role in reducing hospital and emergency department (ED) visits related to RSV.
Researchers employed a test-negative case-control design among adults aged 60 years and older presenting with acute respiratory illness (ARI) requiring hospitalization or ED evaluation. RSV infection was identified through laboratory testing, and only patients with confirmed RSV served as cases. Controls tested negative for RSV and other key respiratory pathogens, including influenza, SARS-CoV-2, and human metapneumovirus, and positive for a non–vaccine-preventable pathogen.
The analysis focused on individuals who had received the RSVpreF vaccine at least 21 days before illness onset. Vaccine effectiveness (VE) was estimated using multivariable logistic regression, adjusting for demographic and clinical confounders. Out of 8965 ARI encounters included, 7.8% were RSV positive. Among those testing positive, only 0.3% had received the RSVpreF vaccine compared with 3.6% of controls.
The study demonstrated an adjusted VE of 92% (95% CI, 64%-98%) against RSV-related ARI leading to hospitalization or ED visits. Protection remained robust across clinically important subgroups. Among patients with underlying medical conditions—such as chronic lung or cardiovascular disease—VE was 92% (95% CI, 65%-98%). Effectiveness was even higher among adults aged 75 years and older, at 95% (95% CI, 60%-99%). The vaccine also maintained strong protection against critical outcomes, including intensive care unit admission, mechanical ventilation, respiratory failure, vasopressor use, or death, with a VE of 90% (95% CI, 16%-99%).
When focusing on patients experiencing severe disease, defined by oxygen supplementation during the ED visit or hospitalization, RSVpreF achieved a VE of 92% (95% CI, 35%-99%). According to the authors, “The RSVpreF vaccine was 92% effective against both RSV-related ARI ED visits/hospitalizations and severe ARI in this older adult real-world population, indicating that it has higher VE against severe outcomes than other current respiratory vaccines, including SARS-CoV-2, influenza, and pneumococcal vaccines.”
For pharmacists involved in vaccination strategy and patient counseling, these findings underscore RSVpreF’s strong protection profile across populations at the greatest risk for severe respiratory outcomes. Unlike other respiratory vaccines where effectiveness declines with advancing age, this study showed no evidence of waning protection in the oldest adults. This distinction is particularly relevant for pharmacists recommending immunizations to patients aged 75 years and older or those with chronic comorbidities.
In addition, the study’s real-world setting enhances its practical value for clinical decision-making. With hospitalization risk reduction consistent across all subgroups, the data support RSV vaccination as a key preventive measure heading into future respiratory virus seasons.
As public health authorities consider expanding RSV vaccination recommendations to include adults 50 to 59 years old, continued surveillance of RSVpreF’s impact will be critical. The authors concluded that these findings “indicate potential for a substantial population-level impact on severe RSV-related illness among older adults with sustained vaccine uptake.”
Reference
Tartof SY, Aliabadi N, Goodwin G, et al. Estimated vaccine effectiveness for respiratory syncytial virus–related acute respiratory illness in older adults: findings from the first postlicensure season. Clin Infect Dis. 2025;Oct 21:ciaf496. doi: 10.1093/cid/ciaf496
