A Randomized, Placebo-Controlled Trial to Evaluate the Safety and Efficacy of VIR-2482 in Healthy Adults for Prevention of Influenza A Illness (PENINSULA).

Background: Influenza A results in significant morbidity and mortality. VIR-2482, an engineered human monoclonal antibody with extended half-life, targets a highly conserved epitope on the stem region of influenza A hemagglutinin, and may protect against seasonal and pandemic influenza.
Methods: This double-blind, randomized, placebo-controlled, phase 2 study examined the safety and efficacy of VIR-2482 for seasonal influenza A illness prevention in unvaccinated healthy adults. Participants (N = 2977) were randomized 1:1:1 to receive VIR-2482 450 mg, VIR-2482 1200 mg, or placebo via intramuscular (IM) injection. Primary and secondary efficacy endpoints were the proportions of participants with reverse transcriptase-polymerase chain reaction (RT-PCR)-confirmed influenza A infection and either protocol-defined influenza-like illness (ILI) and Centers for Disease Control and Prevention (CDC)-defined ILI or World Health Organization (WHO)-defined ILI, respectively.
Results: VIR-2482 450 mg and 1200 mg prophylaxis did not reduce the risk of protocol-defined ILI with RT-PCR-confirmed influenza A versus placebo (relative risk reduction [RRR], 3.8% [95% CI: -67.3, 44.6] and 15.9% [95% CI: -49.3, 52.3], respectively). At the 1200 mg dose, the RRRs in influenza A illness were 57.2% [95% CI: -2.5, 82.2] using CDC-ILI and 44.1% [95% CI: -50.5, 79.3] using WHO-ILI definitions, respectively. Serum VIR-2482 levels were similar regardless of influenza status; variants with reduced VIR-2482 susceptibility were not detected. Local injection-site reactions were mild and similar across groups.
Conclusion: VIR-2482 1200 mg IM was well tolerated but did not significantly prevent protocol-defined ILI. Secondary endpoint analyses suggest this dose may have reduced influenza A illness.
(© The Author(s) 2024. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)