A new vaccine that could end the need for annual injections against flu has been developed by scientists.
The “universal” vaccine promises to provide long-term protection that could last a lifetime against all types of influenza with just a single injection.
Flu viruses are notoriously difficult to immunise people against as they constantly change and evolve in a way that overcomes currently available vaccines.
Scientists behind the new vaccine, however, claim it can protect against all flu viruses and could help to prevent new strains of the disease from turning into epidemics.
World health officials already fear that a new deadly strain of bird flu in China is a serious threat to human health after it has shown signs of adapting to pass between humans.
The H7N9 flu virus has now infected 131 people and caused 36 deaths.
Tests in animals have shown that the new vaccine is up to ten times as effective than some of the current annual vaccines produced to protect people against winter flu.
Dr Gary Nabel, who led research on the vaccine at the Vaccine Research Centre in Maryland, USA, and now works for drug company Sanofi, said they were now hoping to begin clinical trials on the new vaccine within the next two years.
Dr Nabel, who is leading the team at Sanofi, said: “Influenza viruses pose a significant threat to the public and are a burden on global health systems.
“Each year, influenza vaccines must be rapidly produced to match circulating viruses.
“Our structure-based, self-assembling synthetic nanoparticle vaccine improves the potency and breadth of influenza virus immunity."
He added: "In general, the vaccine would increase the likelihood of protecting against new strains.
"We can't say anything about the H7 virus without further human studies, but in either case, this technology can set the stage for developing universal flu vaccines of this type."
“It provides a foundation for building broader vaccine protection against emerging influenza viruses and other pathogens.”
Currently flu vaccines are produced using predictions about which strains of the virus are likely to be prevalent in the population.
A vaccine that provides protection against the most prevalent strain is produced by growing the virus inside chicken eggs before inactivating it so it cannot cause infections.
The process is slow and expensive, so only the most vulnerable patients are given the vaccine each year. In the UK, elderly patients and pregnant women receive it on the NHS.
Vaccinations work by training the immune system to recognise viruses and mount a defence against them, but the flu virus constantly changes its outer "coat", meaning it can evade detection.
Scientists have for years been attempting to overcome this by producing vaccine that trains the immune system to detect parts of the virus that do not change.
This would allow people to get lifelong protection against many different strains of flu and there are a number currently being tested.
The new universal vaccine attaches eight fragments of virus that are present in all strains of flu to a protein nanoparticle called ferritin.
Dr Nabel and his colleagues, whose work is published in the journal Nature, found their vaccine produced an immune response in ferrets that was ten times Sanofi’s current vaccine. They tested it against six strains of the H1N1 influenza virus.
Scientists gave a cautious welcome to the research, but said trials on humans were needed to see if it worked as well as hoped.
Professor Wendy Barclay, chair in influenza virology at Imperial College London, said the research targeted a "soft underbelly of the virus".
"In short this paper takes us a step closer to believing that a universal flu vaccine is possible, by thinking outside of the box in terms of how to synthesise and manufacture flu vaccines.
“This route could be faster, cheaper and safer than the one we usually use.”
Professor Sarah Gilbert, Professor of Vaccinology, University of Oxford, said: “Overall, the study shows that it is possible to achieve broader immunity to influenza than that obtained with licensed influenza vaccines, which is an important step in the right direction.
“But there is a long way to go before this will make a difference to protecting people against influenza.”
Meanwhile scientists studying the 2009 swine flu pandemic have shown that younger people were most likely to succumb to the disease.
They found the majority of the fatalities occurred in people aged between 25 and 34 years old. This contrasts with winter flu, which takes a greater toll in the over-65s as they are generally more vulnerable to disease.
Dr Andrew Noymer, a public health expert at the University of California Irvine who carried out the study which is published in the journal PLOS ONE, said the findings suggested that older people had higher levels of immunity against the swine flu virus.
This pattern is expected to occur in the next pandemic as older people tend to have been exposed to more viruses during their life and so are more likely to have some immunity against a pandemic strain.
Richard Gray - telegraph.co.uk
