The traditional method of creating flu vaccines involves growing the virus in eggs – but this can be a problem when there are virulent avian flu strains which can kill the eggs used during manufacturing.

During the Covid pandemic, mRNA vaccines were shown to be highly effective at preventing serious illness, and could be produced and altered rapidly, as strains evolved.

Flu pandemics are inevitable, even if the timing of the next global outbreak is uncertain. The flu virus is constantly evolving, which is why a new flu jab is needed every year.

A flu pandemic occurs when the strain shifts, rather than drifts, sufficiently that humans do not have any natural immunity to it.

The last one in 2009, called swine flu, was comparatively mild. But the pandemic of Spanish flu after the First World War killed around 50 million people worldwide.

It is impossible to know if H5N1 will be the strain that causes the next flu pandemic.

There have been other experimental vaccines targeting this strain. I took part in a trial in Oxford in 2006, but the jab, although safe, did not prove to be very effective.

There have been around 1,000 confirmed human cases reported to the World Health Organization since 2003 and nearly half of those proved fatal.

More recently, a strain circulating in the United States caused milder symptoms with eye inflammation being the primary symptoms.

The US government cut $500m of funding for mRNA vaccines in August 2025 after the health secretary, Robert F Kennedy Jr, a vaccine sceptic, said “mRNA technology poses more risks than benefits” for respiratory viruses.

CEPI, the Coalition for Epidemic Preparedness Innovations, has stepped in and provided £40m of funding for the trial.

As part of the deal, Moderna has agreed to guarantee fast and affordable supply of the vaccine to low and middle-income countries in any future pandemic.

CEPI said this would mitigate against the “vaccine nationalism” seen during the Covid pandemic, when millions of people were left unprotected after rich countries snapped up early vaccine supplies.