Single Shot Against Both Influenza and COVID-19 Shows Promise in Phase 3 Trial

A new development in vaccine research could soon simplify protection against two major respiratory illnesses for older adults. A novel multicomponent messenger RNA (mRNA) vaccine, known as mRNA-1083, has demonstrated promising results in a pivotal phase 3 clinical trial, showing it can provide immune protection against both seasonal influenza and COVID-19 with a single injection.

Key Findings from the Phase 3 Study

The phase 3 trial, conducted across the United States, enrolled 8,061 adults aged 50 years and older between October and November 2023. Participants were randomly assigned to receive either the investigational mRNA-1083 vaccine plus placebo or the standard vaccines for influenza and COVID-19.

The study population was divided into two age groups: those aged 50–64 years (58.8% women) and those older than 65 years (54.2% women).

How the Vaccine Works

The mRNA-1083 vaccine combines the components of an mRNA-based influenza vaccine (mRNA-1010) with a second-generation SARS-CoV-2 vaccine. The COVID-19 component encodes the spike glycoprotein’s N-terminal and receptor-binding domains, targeting the Omicron XBB.1.5 variant.

Immunogenicity and Safety

Interim results indicate that mRNA-1083 was noninferior to the standard, separate influenza and COVID-19 vaccines in generating immune responses. In fact, the single-shot vaccine elicited higher immune responses against most influenza strains (A/H1N1, A/H3N2, B/Victoria, and B/Yamagata) and SARS-CoV-2 than the comparator vaccines.

Implications for Public Health

If approved, mRNA-1083 could streamline vaccination campaigns, reduce the number of injections needed, and potentially improve vaccine uptake among older adults—a group at higher risk for complications from both influenza and COVID-191.

Disclaimer

This article is based on interim findings from a phase 3 clinical trial as reported on June 3, 2025. The mRNA-1083 vaccine is still investigational and has not yet received regulatory approval for general use. Clinical outcomes, safety data, and regulatory decisions may change as more evidence becomes available. Individuals should consult healthcare providers for current recommendations on influenza and COVID-19 vaccination.