Moderna, Inc. ( MRNA ) on Monday revealed results from a Phase 3 efficacy study (P304) evaluating the relative vaccine efficacy (rVE) against influenza illness of mRNA-1010, the company’s seasonal influenza (flu) vaccine candidate, compared to a licensed standard-dose seasonal influenza vaccine in adults aged 50 years and older.

mRNA-1010 achieved the most stringent superiority criterion prespecified in the protocol, with an rVE of 26.6% in the overall study population. Additionally, strong rVE was observed for each influenza strain contained in the vaccine, including A/H1N1 (rVE=29.6%), A/H3N2 (rVE=22.2%), and the B/Victoria lineages (rVE=29.1%).

Subgroup analyses confirmed a consistently strong rVE point estimate across age groups, risk factors, and previous influenza vaccination status. In participants aged 65 years and older, mRNA-1010 demonstrated an rVE of 27.4%.

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In a previous Phase 3 study, mRNA-1010 had demonstrated superior seroconversion rates and geometric mean titer ratios (GMR) against all strains included in the vaccine compared to both high-dose and standard-dose licensed seasonal influenza vaccine.

According to the CDC, seasonal flu-related hospitalizations and outpatient visits reached a 15-year high during the 2024-2025 season.

Over 600,000 Americans were hospitalized due to flu-related illness last year, leading to substantial direct and indirect costs and widespread disruption to daily life and work.

The trial enrolled 40,805 adults aged 50 years and older across 11 countries. Participants were randomly assigned to receive either a single dose of mRNA-1010 or a standard-dose licensed comparator, with a median follow-up of six months.

The safety and tolerability of mRNA-1010 were consistent with reported results from a previous Phase 3 study. The majority of solicited adverse reactions (SARs) were mild.

Injection site pain was the most common local SAR, and fatigue, headache, and myalgia were the most common systemic SARs reported.

There were no significant differences between the groups in the rates of unsolicited adverse events, serious adverse events, or adverse events of special interest.

Moderna ( MRNA ) plans to present these data at an upcoming medical conference and submit them for peer-reviewed publication. The company will engage with regulators on filing submissions for mRNA-1010.

Earlier this month, the U.S. Food and Drug Administration (FDA) expanded approval of Moderna’s respiratory syncytial virus vaccine to adults aged 18-59 at increased risk for disease.

The mRNA-based shot showed significant immune responses in adults with underlying health conditions and maintained a favorable safety profile. The vaccine was previously limited to adults 60 and older, where it demonstrated 79% efficacy against RSV symptoms.

Price Action: MRNA stock is up 3.31% at $28.06 during the premarket session at last check Monday.

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