The first UK volunteers have received a bird flu vaccine in a clinical trial aimed at protecting against a possible pandemic.
The jab targets the H5N1 strain of flu, a form of bird flu that has caused major outbreaks in birds worldwide and has also spread to some mammals.
The risk to humans is currently low, according to the UK Health Protection Agency, with almost all human cases linked to close contact with infected animals.
The vaccine uses mRNA technology, the same approach used in Covid jabs, which gives the body instructions to recognise a virus. Scientists say this means it can be made quickly and at scale in the event of a pandemic.
The trial aims to recruit people who work in the poultry industry or are over 65, the two groups considered most at risk. It will involve 4,000 volunteers in total, with three quarters recruited at 26 sites in England and Scotland, and the rest in the US.
Dr Rebecca Clark, the trial’s national co-ordinating investigator, based at Layton Medical Centre in Blackpool, said the strain was “evolving and spreading across animal species”.
“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.
There have been 116 confirmed human cases around the world since 2024, almost all linked to close contact with infected animals. S
ince 2003, the World Health Organization has recorded around 1,000 confirmed human cases, nearly half of which proved fatal.
More recently, a strain circulating in the US has caused milder symptoms, with eye inflammation as the main symptom.
The study will examine whether the vaccine is safe and whether it can trigger a strong immune response, meaning the body’s defence system reacts well to it.
If it can, the vaccine could then be licensed for use if needed.
Professor Lucy Chappell, chief scientific adviser at the Department of Health and Social Care and chief executive officer of the National Institute for Health and Care Research, said the trial was “bolstering our pandemic resilience”.
If the vaccine is needed, it would be made at Moderna’s new plant at Harwell in Oxfordshire, which currently produces Covid vaccines for the UK.
The site can make 100 million doses a year, but in a pandemic that could rise to 250 million.
The traditional way of making flu vaccines involves growing the virus in eggs, but this can become a problem when there are virulent avian flu strains, meaning severe bird flu strains, that can kill the eggs used in manufacturing.
During the Covid pandemic, mRNA vaccines were shown to be highly effective at preventing serious illness and could be produced and adapted quickly as strains evolved.
Flu pandemics are considered inevitable, even if no one knows when the next global outbreak will happen.
The virus is constantly evolving, which is why a new flu jab is needed each year. A flu pandemic happens when the strain changes so much that humans have little or no natural immunity to it.
The last such event, swine flu in 2009, was comparatively mild. But the Spanish flu pandemic after the First World War killed around 50 million people worldwide. It is impossible to know whether H5N1 will be the strain behind the next flu pandemic.
There have been other experimental vaccines targeting this strain.
A trial in Oxford in 2006 found one jab was safe but did not prove very effective.
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