A "Universal" Flu Vaccine

A "universal" flu vaccine that protects against many strains of the virus could be available within a few years, scientists have said. Early safety trials of the vaccine have already started and it could be tested on patients as early as 2013.

Working with mice, ferrets and monkeys, The US team "primed" the immune system of mice, ferrets and monkeys with a "base" of influenza DNA. They added a "booster" consisting of a regular seasonal flu vaccine which increased and broadened its immunity. The vaccine's effectiveness improved each year until, theoretically, recipients would be immune to flu.

The "priming" or base vaccine came from a 1999 virus but antibodies were generated that neutralised viruses of different sub-types and from different years. Mice and ferrets were able to fight off viruses dating from before 1999, including the deadly strain of 1934, and also strains from 2006 and 2007. The vaccine was also effective against H5N1 "bird flu".

The study leader, Dr Gary Nabel,  from the US National Institute of Allergy and Infectious Diseases in Bethesda, Maryland, said: "We are excited by these results."

"The prime-boost approach opens a new door to vaccinations for influenza that would be similar to vaccination against such diseases as hepatitis, where we vaccinate early in life and then boost immunity through occasional, additional inoculations in adulthood.

"We may be able to begin efficacy trials of a broadly protective flu vaccine in three to five years.” The scientists measured how well the prime-boost vaccine protected mice and ferrets against deadly levels of flu virus.

Three weeks after receiving the boost, 20 mice were exposed to high levels of 1934 flu virus and 80 per cent survived. When mice were given only the “prime” or “boost” elements alone, or a sham vaccine, all died. Similar results were seen in ferrets, which are good predictors of flu vaccine effectiveness in humans.

Flu viruses are notorious for their ability to mutate and become resistant to vaccines. Antibodies target a lollipop-shaped flu virus surface protein called haemagglutinin (HA). But the structure of the protein’s “head” mutates readily, allowing the virus to go undetected when it changes form. The new vaccine generates “universal” antibodies that aim for the “stick” of the HA lollipop, which varies little from strain to strain.

Professor John Oxford, Britain’s leading flu expert and a virologist at St Bart’s and Royal London hospitals, said: “This is something that we have been after for a long time but the next stage is crucial. Many new vaccines fall at the human trial stage.”

Professor Hugh Pennington, Britain’s leading microbiologist, of Aberdeen University, said: “It is an exciting and attractive approach. We really do desperately need something along these lines. It is a nice idea but the proof will be in the pudding and seeing whether it works in humans.”