Nurses prepare influenza vaccine injections during a flu shot clinic in Boston, Massachusetts.

Minor strains of flu which are not covered by vaccination piggyback on major variants to infect us at the same time, research has found.

Current flu jabs target the dominant strains of the virus because these infect the largest number of people. However scientists have discovered that these are often mixed in with minor variants – which can have equally serious effects .

Professor Elodie Ghedin, from New York University’s College of Global Public Health, said: ‘A flu infection is not homogeneous, but rather a mix of strains that gets transmitted as a swarm. Vaccines target the dominant strains... but our findings reveal an ability of minor strains to elude these vaccines.’

Research by Professor Ghedin’s team, published in the journal Nature Genetics, looked at samples from flu cases in Hong Kong in 2009. All carried minor strains, as well as variants of major and minor.

The flu jab – typically given to more vulnerable groups – costs the NHS around £100million a year.

 

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