Health and Medicine
PUBLISHED
An mRNA vaccine for avian influenza, developed by pharma company Moderna, has begun Phase 3 human trials. Building on the same technology used in their highly successful COVID-19 vaccine, the aim is to shore up the world’s defences against what is widely considered to be one of the biggest viral threats facing humanity.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.The H5N1 subtype of influenza A, often referred to as just “bird flu” because of its species’ of origin, has shown it has the capability to adapt to many different animals, feathered and non-feathered alike. Starting in 2024, reports came in from US dairy farms of cattle becoming infected, followed by a small but concerning number of human infections. Species as diverse as alpacas, cats, and seals have all been affected.
Because of this multi-species spread, and because history has shown us the devastation that flu can bring, health authorities around the world are concerned about the virus’s pandemic potential.
“We know that the A(H5N1) strain is evolving and spreading across animal species, and though it does not yet move easily between humans, we have to treat human-to-human transmission as a real possibility. This trial is our proactive attempt to shield against that possibility, and any future pandemic that could emerge from it,” said Dr Rebecca Clark in a statement. Clark is the national coordinating investigator for the new vaccine trial in the UK.
We already have seasonal flu vaccines – you may well have received one yourself. They’re updated every year because flu viruses mutate and evolve, so the circulating viral strains change from one winter to the next. Should a flu pandemic hit again, that does leave us in an arguably better position than we were in with COVID-19, a virus that was completely new to us for which no vaccine existed. But there’s still a lot of room for improvement.
Many groups of scientists are working on new flu vaccine platforms and “universal” vaccines that could protect against most or all potential future strains. One promising platform is the mRNA vaccine technology that saw so much success with COVID-19.
Moderna’s mRNA COVID vaccine is one of those that helped turn the tide of the pandemic, and it’s still in use today. It seems a fairly natural next step for them to turn their attention to flu.
But mRNA vaccines have also received strong pushback – notably, from US Health and Human Services Secretary Robert F. Kennedy, Jr. Last year, his department pulled millions of dollars of mRNA vaccine funding in what was described as a “coordinated wind-down” of this research.
In a statement at the time, Kennedy claimed – against the scientific consensus – that “these vaccines fail to protect effectively against upper respiratory infections like COVID and flu.” Quite apart from the promising trials of mRNA flu vaccine candidates, we now have years’ worth of real-world COVID vaccine data to prove this is not the case.
mRNA vaccine researchers have also had to fight a tide of misinformation about the technology, including incorrect claims that these products can alter human DNA, something that’s categorically impossible.
In this tricky landscape, funding support for this Phase 3 trial of Moderna’s candidate vaccine has come from CEPI, the Coalition for Epidemic Preparedness Innovations. They’ve put forward up to $54.3 million to assist with development and licensure, and support efforts to ensure that this vaccine will be made available wherever it is needed. Moderna has pledged to reserve 20 percent of its H5 bird flu vaccine capacity for supply to low and middle-income countries at an affordable price, should the vaccine be licensed.
The trial will eventually include around 4,000 volunteers, the first of whom have already been receiving doses of the vaccine at a center in the UK city of Southampton. One such volunteer is physiotherapist Clare Howard, who keeps a backyard flock of chickens.
“Novel viruses are just so dangerous,” she said. “With COVID, we didn’t have the time to prepare, so it’s great to be able to do something now that will contribute to protecting society.”
Speaking to the UK Science Media Centre, Professor John Tregoning of Imperial College London elaborated on the potential threat this virus poses.
“Existing strains (if they do infect people, which fortunately is relatively rare at the moment) often cause very severe disease in humans, much more serious than the virus strains that cause influenza infections in the winter. Secondly, most people do not have any pre-existing immunity to the H5N1 viruses – as we saw during the COVID pandemic, when people lack immunity, viruses spread faster and cause more disease.”
“One of the key lessons from the COVID was that speed of response is critical for saving lives. Doing a large scale human vaccine trial for H5N1 now, allows for a more rapid scale up of response if the virus spreads in the future. Another lesson from the COVID pandemic was that RNA vaccines can be scaled up very rapidly, so testing this platform for this infection is a good precaution.”
The estimated completion date for the trial is January 2027.
