Immunogenicity of Combined Flu/COVID-19 Vaccine Noninferior to Components in Older Adults
The investigational mRNA-1083 vaccine induced superior immune responses against all 4 flu strains in adults aged 50-64 years and against 3 in adults 65 and older.
The Moderna investigational multicomponent vaccine that combines protection against seasonal influenza and COVID-19 generated noninferior immune responses compared to separate standard vaccines, according to interim phase 3 data data from a trial involving more than 8,000 adults aged 50 years and older.1
©Desertsands/stock.adobe.com
Results from the study, published online May 7 in JAMA, showed that compared to standard-dose and high-dose influenza vaccines, mRNA-1083 not only met noninferiority criteria but also induced superior immune responses against all 4 influenza strains in adults aged 50-64 years and against 3 clinically relevant influenza strains in those 65 and older, The vaccine also elicited stronger immune responses against SARS-CoV-2 across all age groups, according to the findings.1
The randomized, observer-blinded trial, conducted between October and November 2023 across 146 US sites, enrolled 8,015 participants divided into 2 age cohorts: 4,017 adults aged 65 and older and 3,998 adults aged 50-64. Researchers randomly assigned participants in a 1:1 ratio to receive either mRNA-1083 plus placebo or coadministered licensed vaccines - high-dose quadrivalent inactivated influenza vaccine (HD-IIV4) for those 65 and older, standard-dose IIV4 (SD-IIV4) for those 50-64, and mRNA-1273 COVID-19 vaccine for all participants.1
Study authors described the demographics of the trial population as diverse, with the 65 and older cohort having a median age of 70 years and comprised of 54.2% women, 18.4% Black or African American participants, and 13.9% Hispanic or Latino participants. The 50-64 age group had a median age of 58 years, with 58.8% female, 26.7% Black or African American, and 19.3% Hispanic or Latino participants.1
The safety and immunogenicity findings are from the planned interim analyses after all participants had completed the day 91 visit, as stated in the published study. Immunogenicity data are reported from days 1 and 29. Data from the final analysis (through the day 181 visit) will be reported separately.
Single-Shot Immunogenicity Noninferior
The assessment of immunogenicity showed that mRNA-1083 achieved noninferiority against all vaccine-matched influenza and SARS-CoV-2 strains based on strict statistical criteria - specifically, the lower bound of the 97.5% confidence interval of the geometric mean ratio greater than 0.667 and the lower bound of the 97.5% confidence interval of the seroconversion/seroresponse rate difference greater than -10%.1
The combined vaccine did show higher rates of solicited adverse reactions compared to the standard vaccines in both age cohorts. Among adults 65 and older, 83.5% reported reactions with mRNA-1083 versus 78.1% with comparator vaccines. Similarly, in the 50-64 age group, 85.2% reported reactions with mRNA-1083 compared to 81.8% with standard vaccines. However, researchers noted that the severity of most adverse reactions, which included injection site pain, fatigue and headaches, was mild to moderate and they were transient. No significant safety concerns emerged during the trial period.1
The mRNA technology is used in approved COVID-19 and RSV shots, but has not yet been approved for a flu shot.
The findings are based on measuring antibodies in participants’ blood 29 days after receiving the shot, an indication of short-term disease protection. Last week, Moderna pushed its target date for the vaccine's approval to 2026 after the FDA requested specific data on the ability of the vaccine to reduce risk of disease, according to a report from the AP.2
Nonetheless, study authors concluded that the results suggest that mRNA-1083 could provide a viable alternative to separate vaccinations against influenza and COVID-19 for adults over 50, potentially simplifying the immunization process while maintaining or improving immune protection.1
