For the millions of adults living with compromised immune systems — whether from cancer treatment, organ transplantation, HIV, or autoimmune therapies — RSV has long posed a disproportionate and largely underappreciated threat. Until now, evidence-based guidance for this high-risk population has been sparse. A landmark 2025 IDSA guideline changes that calculus significantly, offering the first systematic evidence-based framework specifically designed for immunocompromised individuals ahead of the 2025–2026 respiratory virus season.
A multidisciplinary expert panel convened by the Infectious Diseases Society of America conducted a systematic review of comparative effectiveness and safety data spanning August 2024 through July 2025, supplemented by the Vaccine Integrity Project dataset. Two test-negative case-control studies in immunocompromised adults found RSV vaccination associated with a 70% reduction in RSV-related hospitalization (95% CI: 66%–73%). Indirect evidence drawn from older-adult populations — a population with some immunological overlap — demonstrated 81% effectiveness against critical illness (95% CI: 52%–92%). Safety data across three randomized trials showed serious adverse events were statistically comparable between vaccinated and unvaccinated participants. Guillain-Barré syndrome, the primary safety concern flagged in broader RSV vaccine surveillance, occurred at an estimated rate of 11 excess cases per million doses. On this basis, the panel issued a strong recommendation — graded using the GRADE methodology — for age-appropriate RSV vaccination in immunocompromised adults and adolescents.
This guidance is clinically meaningful for several reasons. First, it addresses a long-standing gap: immunocompromised individuals are routinely excluded from the pivotal trials that generate approval-level efficacy data, leaving clinicians to extrapolate from healthier populations. The 70% hospitalization reduction is particularly striking given that immune blunting often attenuates vaccine responses in this group. Second, the GRADE-based strong recommendation signals that the benefit-to-risk calculation is considered robust despite the acknowledged evidence limitations. The primary caveat is that the underlying studies are observational and case-control in design — not randomized trials in this specific population — meaning residual confounding cannot be excluded. The pediatric immunocompromised population remains more data-limited, and the panel's recommendations for children likely carry greater uncertainty. Overall, this represents a meaningful, clinically actionable advance rather than an incremental refinement.