Moderna begins phase 3 trial of mRNA bird flu vaccine

Wednesday 22 April 2026 - 10:00

By: Dakir Madiha

Moderna begins phase 3 trial of mRNA bird flu vaccine

Moderna has launched a phase 3 clinical trial of its mRNA based vaccine targeting pandemic bird flu, marking a significant step in efforts to prepare for potential global outbreaks. The company confirmed that the first participants have received doses of the candidate vaccine mRNA 1018, the first mRNA vaccine designed specifically for pandemic influenza to reach late stage testing.

The study aims to enroll about 4,000 healthy adults aged 18 and older across the United States and the United Kingdom. It is structured as a randomized, observer blind, placebo controlled trial to assess both safety and immune response. Around 75 percent of participants will be recruited in the United Kingdom, with priority given to individuals over 65 and poultry workers, groups considered at higher risk of exposure to avian influenza.

The trial is supported by up to 54.3 million dollars in funding from the Coalition for Epidemic Preparedness Innovations, which stepped in after US federal support was withdrawn in 2025. The Department of Health and Human Services had terminated more than 700 million dollars in contracts related to the vaccine, arguing that continued investment in the mRNA H5N1 program was not justified. The funding cuts included earlier allocations made in 2024 and early 2025, creating a gap later filled by international partners focused on pandemic readiness.

Early stage results have shown strong immune responses. In a phase 1 and 2 study involving roughly 300 healthy adults, nearly 98 percent of participants achieved protective antibody levels within 43 days after two doses. This represented a more than forty fold increase compared with baseline levels. The company also plans to use data from advanced trials of its seasonal flu vaccine to support potential regulatory approval for the pandemic candidate.

The United Kingdom portion of the study is backed by national health research institutions as part of a broader partnership between Moderna and the government. The primary completion date is expected in January 2027. The trial comes as concerns persist over the spread of H5N1 among birds and livestock, with a rising number of human infections reported, particularly among agricultural workers.

If successful, the vaccine could offer a faster and more scalable alternative to traditional egg based influenza vaccines. Public health experts view rapid production capacity as critical in responding to a pandemic, where timing can determine the scale of global impact. The mRNA approach may allow vaccines to be designed and manufactured more quickly, improving preparedness for future outbreaks.