Ferguson, M., et al. Immune persistence and safety of the AS01E-adjuvanted respiratory syncytial virus prefusion F protein-based vaccine in adults 50-59 years of age, including at-increased-risk adults: A randomized controlled trial. Hum Vaccin Immunother, 2025 Dec, 21(1):2579335. PMID: 41194599
Respiratory syncytial virus (RSV) is a leading cause of respiratory illness across all age groups, particularly affecting infants, older adults, and individuals with chronic health conditions, resulting in significant morbidity and healthcare burden. Despite the availability of vaccines for older adults, there remains a need to evaluate their efficacy and safety in middle-aged populations at increased risk for severe RSV disease. This study aims to assess the immunogenicity, durability of immune responses, and safety profile of the adjuvanted RSVPreF3 vaccine in adults aged 50–59, including those with underlying health conditions, to inform broader vaccination strategies. The importance of this research lies in its potential to extend protective benefits to a previously underrepresented age group, thereby helping to reduce RSV-related disease burden and improve public health outcomes.
The study demonstrated that a single dose of the adjuvanted RSVPreF3 vaccine in adults aged 50–59 elicited a robust humoral and cell-mediated immune response that persisted for at least 12 months post-vaccination, with antibody titers and T-cell responses remaining above baseline and placebo levels. Immune responses were comparable to those observed in adults aged 60 and above, in whom efficacy had been previously established. Safety data showed an acceptable 12-month profile, with only one vaccine-related serious adverse event (hemolytic anemia) and no vaccine-related deaths reported. These findings support the vaccine’s potential for long-term protection and safety in this middle-aged, at-risk population.
The paper discusses QS-21 as a component of the AS01E adjuvant system, highlighting its role in eliciting an immune response. Specifically, QS-21 is a saponin adjuvant that, along with liposomes and MPL (3-O-desacyl-4′-monophosphoryl lipid A), forms the AS01E adjuvant system used in the RSVPreF3 vaccine. The inclusion of QS-21 is intended to enhance the vaccine’s immunogenicity by stimulating both humoral and cell-mediated immunity. Although the paper focuses on the immunogenicity and safety outcomes, it references the role of AS01E containing QS-21 in inducing a strong and durable immune response, as demonstrated in previous studies.
These findings support the potential of the vaccine to help prevent RSV-related disease in middle-aged adults, with implications for broader use in populations at increased risk. Further studies are suggested to evaluate its benefits in younger populations and those with immunocompromising conditions.
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