Concomitant administration may improve vaccination rates. This analysis of a phase 1/2 randomized study included 1073 healthy ≥65-year-olds who previously received ≥3 mRNA COVID-19 vaccine doses. Participants received concomitantly administered RSVpreF and bivalent BA.4/BA.5-adapted BNT162b2 vaccine (concomitant administration) with or without quadrivalent influenza vaccine (QIV), admixed combined RSVpreF + BNT162b2 vaccine (combined vaccine) with or without QIV, RSVpreF, BNT162b2, or QIV. Immunogenicity objectives included demonstrating the noninferiority of neutralizing antibody titers elicited by concomitant administration and combined vaccine compared with RSVpreF or BNT162b2 administered alone, and by concomitant administration and combined vaccine given with QIV compared with RSVpreF, BNT162b2, and QIV alone. Reactogenicity (≤7 days) and safety ≤1 month (adverse events (AEs)) and ≤6 months (serious AEs (SAEs)) after vaccination were assessed. Noninferiority for all immunogenicity comparisons was demonstrated. All vaccine groups were well tolerated; no new safety concerns were identified. Reactogenicity was mostly mild/moderate with rates generally similar across groups, except injection site pain and fatigue, which were less frequent with RSVpreF + placebo vs. other groups. AEs were infrequent, mostly mild/moderate, occurring at similar frequencies across groups. No AEs leading to study withdrawal or vaccine-related SAEs were reported. Favorable safety and tolerability alongside similar immunogenicity provide support for concomitant or combined use of RSVpreF and BNT162b2, with or without QIV, to help protect older adults from these important respiratory pathogens (NCT05886777).

Introduction Infants and young children typically have the highest age-related risk of invasive meningococcal disease. The immunogenicity and safety of a single primary dose and a booster of a meningococcal A/C/W/Y tetanus toxoid conjugate vaccine (MenACWY-TT; Nimenrix^®) in infants were evaluated. Methods In this phase 3b, open-label, single-arm study, healthy 3-month-old infants received a single Nimenrix dose followed by a booster at age 12 months (1 + 1 series). Functional antibodies before and 1 month after each vaccination were evaluated with serum bactericidal antibody assays using rabbit (rSBA) or human (hSBA) complement for each A/C/W/Y serogroup. Primary endpoints were rSBA seroprotection (titers ≥ 1:8) rates and geometric mean titers (GMTs); supportive secondary endpoints included hSBA seroprotection (titers ≥ 1:4) rates and GMTs. Local reactions and systemic events occurring within 7 days, adverse events (AEs), serious AEs, and newly diagnosed chronic medical conditions following vaccination were assessed. Results Overall, 147 and 143 participants received the primary and booster Nimenrix doses, respectively. rSBA seroprotection rates across serogroups were 82.3–91.1% at 1 month after the primary dose and increased to 100% at 1 month after the booster. rSBA GMTs were considerably higher after the booster (1299.5‒2714.1) than after the primary dose (54.7‒202.4). In hSBA evaluations performed as supportive to rSBA evaluations, seroprotection rates increased from 38.8 to 95.5% after the primary dose to 100% after the booster, with corresponding GMT increases (8.8‒149.8 to 1208.4‒7299.6). Local reactions and most systemic events were mild to moderate in severity; no new safety concerns were identified. Conclusion Nimenrix given at ages 3 and 12 months had a favorable safety profile and elicited protective immune responses and robust anamnestic booster responses across A/C/W/Y serogroups. These results provide important support for this alternative Nimenrix 1 + 1 immunization schedule for infants < 6 months, allowing flexibility in infant meningococcal immunization. Trial Registration ClinicalTrials.gov, NCT04819113.