NO SAFETY CONCERNS OBSERVED WHEN THE ADJUVANTED RECOMBINANT ZOSTER VACCINE (RZV) AND THE COVID-19 MRNA-1273 BOOSTER WERE CO-ADMINISTERED IN ≥50-YEAR-OLDS

INTRO: The US CDC recommends that COVID-19 vaccines may be coadministered with other age-appropriate vaccines. There is limited data assessing outcomes, including reactogenicity, on such co-administration. For the first time, we present interim safety data of RZV administered concomitantly or sequentially with an mRNA-1273 booster vaccine. METHODS: In this phase 3, randomized, open-label, multi-center study (NCT05047770), adults aged ≥50 years were randomized 1:1 to receive the first RZV dose with mRNA-1273 booster (50 μg) at day 1 and the second RZV dose at week (W)8 (Co-Administration group [Co-Ad]), or mRNA-1273 at day 1, the first RZV dose at W2 and the second RZV dose at W10 (Sequential group [Seq]). Descriptive analyses of solicited/unsolicited adverse events (AEs) with onset within 7/30 days post-mRNA-1273 or first RZV dose, and of serious AEs/potential immune-mediated diseases/AEs of special interest (SAEs/pIMDs/AESIs) reported until database freeze are reviewed. FINDINGS: The exposed set comprised 267 (Co-Ad) and 272 (Seq) participants. In each group, most solicited AEs were mild/moderate in intensity and each with ≤2.5 days median duration, the most frequent were injection site pain, myalgia, and fatigue. Unsolicited (vaccines-related) AEs were reported by 25.0% (2.9%) of participants post-mRNA-1273 in Seq, 25.2% (0.8%) post-RZV in Seq, and 37.1% (3.7%) in Co-Ad. SAEs/pIMDs/AESIs were reported for 6/1/2 participants in Co-Ad and 5/1/3 in Seq. In Seq, one SAE/AESI (pulmonary embolism) and one pIMD/AESI (cutaneous vasculitis) occurred 2 and 9 days postmRNA-1273 (before RZV administration), respectively, and were considered mRNA-1273-related by investigators. In Co-Ad, one AESI (chronic hepatitis) occurred 35 days post-second RZV dose, considered vaccines-related by Sponsor. No fatalities occurred. CONCLUSION: No safety concerns were identified. The frequency/severity/type of AEs were comparable between groups and consistent with the known safety profile of each vaccine, whether RZV and mRNA-1273 booster were administered concomitantly or sequentially. Co-administration may enhance vaccine coverage rates. Funding: GSK