Major Trial for Human Bird Flu Vaccine Launches in UK and US

A groundbreaking phase 3 trial has begun in the United Kingdom and the United States to test a new mRNA-based vaccine against the H5N1 strain of avian influenza, commonly known as bird flu. The vaccine, developed by Moderna and designated mRNA-1018, aims to prepare for a potential pandemic by evaluating its safety and efficacy in thousands of adult volunteers.

The trial is actively recruiting approximately 4,000 participants across both countries, with a focus on individuals at higher risk of exposure, including poultry farmers and those over the age of 65. In the UK, 3,000 volunteers will receive the vaccine at 26 sites spanning England and Scotland, although the remaining 1,000 participants will be enrolled in the United States.

Participants will receive two doses of the vaccine administered three weeks apart, and the study is expected to run for seven months. Researchers emphasize that while the H5N1 virus currently does not spread easily between humans, the potential for human-to-human transmission remains a serious concern, warranting proactive vaccine development.

The vaccine uses the same mRNA technology employed in Moderna’s COVID-19 vaccines, which instructs the body to produce specific viral proteins to trigger an immune response. Early trials of mRNA-1018 have shown it to be generally well tolerated, with side effects described as mild to moderate and no significant safety concerns reported.

Health officials, including the UK Health Protection Agency, note that nearly all confirmed human cases of H5N1 since 2024 have been linked to close contact with infected animals, such as birds, dairy cows, or other mammals. Although, the virus’s increasing presence in mammalian species—including mink and marine mammals—has heightened vigilance about its pandemic potential.

Dr Rebecca Clark, the trial’s national co-ordinating investigator based at Layton Medical Centre in Blackpool, stated that although sustained human transmission has not yet been observed, the evolving nature of the virus necessitates preparedness. “Although it does not yet move easily between humans, we have to treat human-to-human transmission as a real possibility,” she said. “This trial is our proactive attempt to shield against that possibility, and any future pandemic that could emerge from it.”

As of the latest reports, there have been 116 confirmed human cases of H5N1 globally since 2024, almost all resulting from direct exposure to infected animals. The ongoing trial represents a critical step in global pandemic preparedness, leveraging advanced vaccine technology to respond swiftly should the virus gain the ability to spread efficiently among people.

Individuals interested in participating, particularly those working in poultry or livestock industries or aged 65 and over, are encouraged to contact trial sites in their region for enrollment details.