Mexican researchers say the vaccination against seasonal influenza may give some protection against A (H1N1). The limited study found that people who had had a flu jab were far less likely to be sick or die from pandemic influenza than those who had not.

The researchers, who published their findings in the British Medical Journal, stressed that the results should be treated cautiously as the study was extremely limited. The scientists studied 140 people, 60 of whom had been confirmed as having A (H1N1). The team at Mexico's National Institute of Public Health said, "these results are to be considered cautiously and in no way indicates that seasonal vaccine should replace vaccination against pandemic influenza A (H1N1) 2009".
 

The new pandemic flu virus does contain an H1N1 swine flu virus that is a very distant cousin of the H1N1 flu virus that is included in the cocktail provided every year in the seasonal flu vaccine. Other studies have shown that the annual flu jab provides little or no protection against pandemic A (H1N1), also known as Mexican flu. A Canadian study suggested that people who got a seasonal flu jab may be more likely to contract A (H1N1), although the World Health Organisation (WHO) and the US Centers for Disease Control (CDC) have expressed their doubts about the findings.
 

The latest WHO report says that as of 27 September, there have been more than 340,000 laboratory confirmed cases of A (H1N1) across the globe and more than 4,100 deaths. The World Health Organisation says that Mexican flu is about as lethal as ordinary seasonal influenza but warned that the virus could mutate into a form that would make it more deadly.