VACIRiSS RCT finds PCV13 fails to cut infection rehospitalization in 214 sepsis survivors despite variable antibody responses

{"The double-blind trial enrolled adults discharged after sepsis and randomized them to 13-valent pneumococcal conjugate vaccine or saline. Primary endpoints were infection rehospitalization and all-cause mortality at 12 months; secondary endpoints included serotype-specific IgG titers and opsonophagocytic activity measured at baseline, 28 days, and 180 days. Baseline immune phenotyping captured lymphocyte subsets and cytokine profiles to stratify participants.","Overall, vaccinees showed no reduction in the composite endpoint (hazard ratio 0.97, 95% CI 0.68-1.38). Antibody responses varied fivefold; older age, higher BMI, male sex, and elevated baseline IL-6 predicted blunted seroconversion. These patterns align with prior observational cohorts in Critical Care Medicine showing persistent lymphopenia and myeloid suppression persisting beyond 90 days post-sepsis.","The results highlight a missed opportunity in current UK and US post-sepsis pathways that do not integrate vaccination status review. They connect to the Lancet Sepsis Commission findings on the absence of structured follow-up, suggesting that blanket adult immunization schedules may under-serve this population until response biomarkers are validated.","Next steps require adaptive platform trials testing higher-valent conjugates, adjuvanted formulations, or timing adjustments stratified by immune recovery scores, with enrollment targets exceeding 500 participants per arm to detect 15% absolute risk reductions."}