Researchers have discovered that secondary, bacterial infections are far more likely to be fatal, and account for the majority of deaths associated with flu viruses.
This means that the current flu vaccine programme is flawed because it is concentrating entirely on the original virus. Governments spend billions of pounds every year on stocks of anti-virals to protect against seasonal flu as well as the occasional so-called pandemics, such as avian and swine flu.
But in an analysis of the Spanish flu outbreak of 1918 - the most lethal of modern times - researchers have discovered that most deaths were caused by bacterial infections, such as pneumonia.
The same pattern can be seen today, say the researchers from the US's National Institute of Allergy and Infectious Diseases. Of the deaths recorded in the recent swine flu (H1N1) outbreak, around 55 per cent were caused by a secondary bacterial infection.
Governments and drug companies need to go back to the drawing board, and come up with flu shots that include an anti-bacterial, say the researchers.
(Source: Journal of Infectious Diseases, 2010; doi: 10.1086/657144).