British scientists are one step closer to developing a "holy grail" universal flu vaccine that would tackle all strains of the illness.
A successful jab would stimulate the body to create more immune cells capable of attacking the virus and could be effective at preventing new strains that cross into humans from birds and pigs, according to scientists.
Results from the 2009 swine flu pandemic showed patients with more virus-killing immune cells in their blood at the start of the illness, would avoid sever illness, researchers at Imperial College London (ICL) found.
Professor Ajit Lalvani from the National Heart and Lung Institute at ICL, who led the study, said: "New strains of flu are continuously emerging, some of which are deadly, and so the holy grail is to create a universal vaccine that would be effective against all strains of flu."
Influenza kills between 250,000 and 500,000 globally per year, according to the World Health Organisation.