mRNA influenza vaccine outperformed standard-dose comparator

What the study found: mRNA-1010, an investigational messenger RNA (mRNA) influenza vaccine, was more effective than a licensed standard-dose comparator in adults 50 years of age or older. It also caused more solicited adverse reactions than the comparator.
Why the authors say this matters: The authors conclude that mRNA-1010 was superior to standard-dose licensed vaccines for preventing reverse-transcriptase-polymerase-chain-reaction (RT-PCR)-confirmed, protocol-defined influenza-like illness in this age group.
What the researchers tested: In this phase 3, double-blind, active-controlled trial, adults 50 years of age or older were randomly assigned to receive trivalent mRNA-1010 or a licensed standard-dose comparator. The main outcome was relative vaccine efficacy against RT-PCR-confirmed, protocol-defined influenza-like illness caused by influenza A or B from at least 14 days after vaccination through the end of the influenza season.
What worked and what didn't: Among 40,703 participants, influenza-like illness occurred in 2.0% of mRNA-1010 recipients and 2.8% of comparator recipients, which corresponded to a relative vaccine efficacy of 26.6% and met the trial's criteria for noninferiority, superiority, and higher-level superiority. Solicited adverse reactions were more frequent with mRNA-1010, while serious adverse events were reported in 2.2% of mRNA-1010 recipients and 1.9% of comparator recipients.
What to keep in mind: The abstract describes the trial population as adults 50 years of age or older and reports median follow-up of 181 days. It also notes that solicited adverse reactions were mostly mild to moderate and transient; other limitations are not described in the available summary.

Key points

• mRNA-1010 was superior to a standard-dose licensed influenza vaccine comparator in adults 50 years of age or older.
• RT-PCR-confirmed, protocol-defined influenza-like illness occurred in 2.0% of mRNA-1010 recipients and 2.8% of comparator recipients.
• The relative vaccine efficacy was 26.6% and met criteria for noninferiority, superiority, and higher-level superiority.
• Solicited adverse reactions were more common with mRNA-1010, including injection-site pain, fatigue, headache, and myalgia.
• Serious adverse events were reported in 2.2% of mRNA-1010 recipients and 1.9% of comparator recipients.