Seasonal flu vaccine offers 'some protection'
Research from Mexico City suggests that the seasonal flu vaccine may offer some protection against swine flu, particularly the most severe complications of the disease.
The research team involved admits that the study has several limitations - and that the findings should be considered cautiously "and in no way indicate that seasonal vaccine should replace vaccination against pandemic influenza A/H1N1 2009".
Having put those markers down, it's nonetheless an interesting bit of research which needs further examination. The study was led by Dr Jose Luis Valdespino from Mexico and investigated the link between the 2008-9 seasonal flu vaccine with cases of influenza A/H1N1 during the epidemic in a speciality hospital in Mexico City.
The authors say the reason the seasonal vaccine seems to offer some protection is because it boosts existing antibodies in individuals who have previously been exposed to a similar flu virus, either by infection or vaccination.
They compared the health outcomes (hospitalisation, mechanical ventilation and death) of 60 patients with swine flu and 180 control patients with other diseases (note the small numbers). Both groups of patients informed the authors directly, by telephone or via a close relative whether they had received the 2008-9 seasonal flu vaccine.
The results suggest that the uninfected participants were significantly more likely to have received the seasonal flu vaccine and that it protected them against particularly severe forms of swine flu. However, the authors say the results must be taken in context and argue that given the small sample size "it will be key to conduct similar studies in other settings to confirm or refute our results."
In an accompanying editorial, Dr Menno de Jong from the concurs with Dr Valdespino that the results do not mean that there is no need for a specific vaccine against swine flu.
So what is the take-home message? Well, if you have a seasonal flu jab every winter, there's just a chance that it might protect you against the complications of H1N1 swine flu.
But if you are in an at-risk group, you should not see this as an alternative to having a swine flu vaccine. Indeed, the majority of those who will be offered the swine flu jab this autumn will be asked to roll up both sleeves. In one arm, they will be given the H1N1 swine flu (pandemic) vaccine and in the other, the annual seasonal flu jab. Those at risk of complications of flu need both because there will be several strains of flu doing the rounds over the coming months.
Dr John McCauley from the National Institute for Medical Research in north London said:
"The results look interesting. There does seem to be some degree of protection from the seasonal flu vaccine but it's in an unusual age group, the 41-60-year-olds. In the young and old, it didn't seem to make a difference. It definitely does not mean that people should rely on the seasonal flu vaccine, especially since the pandemic vaccine will be rolled out shortly."
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