Safety and durability of influenza and SARS-CoV-2 antibody responses through 6 months after a single dose of mRNA-1083, a multicomponent influenza and COVID-19 vaccine, in adults ≥50 years

May 29, 2026Human vaccines & immunotherapeutics

Safety and lasting flu and COVID-19 antibody responses up to 6 months after one dose of a combined flu and COVID-19 vaccine in adults 50 and older

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Abstract

mRNA-1083 induced durable immune responses against both influenza and SARS-CoV-2 in adults aged ≥50 years through 6 months.

HAI titers for all vaccine-matched influenza strains were maintained for 6 months and were generally comparable to or higher than those from comparator vaccines.
SARS-CoV-2 neutralizing antibody responses remained higher for mRNA-1083 compared to comparator vaccines over the 6-month period.
Most reactogenicity events were mild to moderate (grade 1-2) and similar between mRNA-1083 and comparator groups.
No serious adverse events or deaths related to vaccination were reported through 6 months.
Findings suggest mRNA-1083 has an acceptable safety profile while eliciting robust immune responses.

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Seasonal influenza and SARS-CoV-2 continue to contribute substantially to global morbidity and mortality. mRNA-1083 is an investigational multicomponent mRNA vaccine targeting seasonal influenza and SARS-CoV-2. In this phase 3, observer-blind, active-controlled trial (NCT06097273), adults (aged ≥50 y) were randomly assigned (1:1) to receive mRNA-1083 (40 µg; plus placebo) or age-appropriate licensed comparator vaccines for influenza and COVID-19. Two substudies were included: Cohort A (≥65 y) and Cohort B (50-64 y). Primary objectives were to demonstrate noninferiority of mRNA-1083 versus comparators for influenza hemagglutination inhibition (HAI) responses and SARS-CoV-2 neutralizing antibody (nAb; PsVNA) responses at Day 29 after vaccination and to evaluate safety and reactogenicity of study vaccines. Here, we report safety, reactogenicity, and immunogenicity of mRNA-1083 through Day 181 in adults aged ≥50 y. mRNA-1083 induced HAI titers against all vaccine-matched influenza strains that were maintained through 6 months and were generally comparable to, or higher than, comparator responses. SARS-CoV-2 nAb responses remained higher for mRNA-1083 than comparators through 6 months. Reactogenicity was predominantly grade 1-2 in severity, and vaccination-related unsolicited adverse events were similar between groups. No serious adverse events or deaths related to vaccination were reported through 6 months. In adults aged ≥50 y, mRNA-1083 elicited durable influenza and SARS-CoV-2 humoral immune responses with an acceptable safety profile through 6 months. These findings support the use of mRNA-1083 as a multicomponent vaccine.: NCT06097273 (https://clinicaltrials.gov/study/NCT06097273). ClinicalTrials.gov identifier