How flu vaccines are manufactured is making them ineffective, warns a study as the threat of dreaded Aussie flu looms large.
Scientists believe the traditional process using chicken eggs is allowing the virus to escape detection from our immune systems – making it more deadly.
Flu viruses are constantly changing proteins on their surface to avoid being spotted, but the 70-year old technique is helping them, researchers warn.
The US Government-funded study backs up the belief that this annual year’s flu jab isn’t strong enough to fight an aggressive strain which has blighted Australia.
Tests revealed H3N2, currently on its way to Britain and expected to wreak havoc on the NHS this winter, has began to mutate already, hampering the vaccine.
Experts are worried it could pose the same threat to humanity as the Hong Kong flu epidemic in 1968, claimed one million lives.
The US Government-funded study backs up the belief that this annual year’s flu jab isn’t strong enough to fight an aggressive strain which has blighted Australia
For more than 70 years, manufacturers have made the flu vaccine by injecting strains into chicken eggs.
This allows the virus to replicate. The fluid in the eggs is then purified to get enough of the virus to use in vaccines.
The need to find new ways
But researchers at The Scripps Research Institute claim their new findings support the case for alternative ways of growing the virus.
Lead author Dr Nicholas Wu said: ‘Now we can explain – at an atomic level – why egg-based vaccine production is causing problems.’
Dr Ian Wilson, also involved in the study, added viruses have to evolve to grow in the egg environment, meaning they mutate to develop better.
They found the egg-based process causes the virus to develop a mutation, called L194P, on one of its key proteins – hemagglutinin glycoprotein.
How does it mutate?
This mutation disrupts the region on the protein that is commonly recognized by our immune system, they wrote in PLoS Pathogens.
This means a vaccine containing the mutated version of the protein will not be able to trigger an effective immune response.
It strengthens the beliefs that this year’s flu jab isn’t strong enough to fight the H3N2 strain, which is expected to wreak havoc on the NHS this winter
This leaves the body without protection against circulating strains of H3N2, which was behind one of Australia’s worst ever flu seasons.
Australia – whose winter occurs during the British summer – had one of its worst outbreaks on record, with two and a half times the normal number of cases.
Some of the country’s A&E units had ‘standing room only’ after being swamped by more than 100,000 cases of the H3N2 strain.
Official figures are yet to confirm how many people have lost their lives to this year’s outbreak, but 370 deaths have been reported so far.
The elderly with their compromised immune systems are particularly susceptible, and a spike in cases among young children has also been shown.
The flu season in the UK and the rest of the Northern Hemisphere tends to mirror what has happened in Australia and the Southern Hemisphere.
The same strains of the virus will circulate north in time for the British flu season, which typically begins in November and lasts until March.
But there are concerns the vaccine, made by World Health Organisation scientists, will prove to be ineffective as it will not match the H3N2 strain
Scientists create the vaccines in March, based on which flu strains they expect to be in circulation. They are then given out in September.
Some health experts in Australia have blamed the severe outbreak on it having mutated. The vaccine used in the UK will be very similar.
Flu viruses are constantly changing proteins on their surface to avoid detection by the body’s immune system – making it more deadly.
This transformation is called an ‘antigenic shift’ if it’s large enough, and can lead to a pandemic. This was responsible for the swine flu outbreak in 2009.
The Aussie flu is transforming quickly, but not fast enough for experts to describe it as a shift. However, it is slowly building up immunity.