Scientists say their discovery of "super antibody" FI6, which can fight all types of influenza A viruses that cause disease in humans and animals may serve as a turning point in the development of new flu treatments.

Vaccine makers currently have to change the formulations of their flu shots every year to make sure they protect against the strains of the virus circulating. This is a cumbersome process which takes time and money, so the goal is come up with a universal flu vaccine that could protect people from all flu strains for decades, or even for life.

Dozens of companies make influenza vaccines, including Sanofi, GlaxoSmithKline, Novartis, AstraZeneca and CSL. When someone is infected with the flu virus, their antibodies target the virus' hemagglutinin protein, the researchers explained in their study, which was published on Thursday in the journal Science.

"As we saw with the 2009 pandemic, a comparatively mild strain of influenza can place a significant burden on emergency services. Having a universal treatment which can be given in emergency circumstances would be an invaluable asset," said John Skehel of Britain's National Institute for Medical Research, who worked on the study with colleagues from the privately-owned Swiss firm Humabs.

Antonio Lanzavecchia, Humabs' chief scientific officer and director of the Swiss Institute for Research in Biomedicine, said high rates of seasonal flu and the unpredictability of possible future pandemics underlined the need for better treatments that target all flu viruses.

Sir John Skehel, MRC scientist at Mill Hill, told BBC News: "We've tried every subtype of influenza A and it interacts with them all. We eventually hope it can be used as a therapy by injecting the antibody to stop the infection." To make progress toward a universal shot that could be used every year, scientists need to identify the molecular signatures that prompt the development of broadly neutralizing antibodies.

When they identified FI6, they injected it into mice and ferrets and found that it protected the animals against infection by either a Group 1 or Group 2 influenza A virus. "As the first and only antibody which targets all known subtypes of the influenza A virus, FI6 represents an important new treatment option," Lanzavecchia said in a statement.

Researchers in the United States said last year they were having some success with another possible approach to developing a universal flu shot, using a two-step system of a vaccine using DNA to "prime" the immune system and then a traditional seasonal flu shot.