A major new study has cast fresh doubt on the effectiveness of flu vaccination, with researchers warning evidence of high-level protection was ‘elusive', particularly in high-risk patients.
US researchers collated influenza-specific outcomes from 31 studies of flu vaccination, after concerns reporting of non-specific outcomes such as death rates could have over-estimated vaccine benefits. Their systematic review, published this week by Lancet Infectious Diseases, estimated immunisation with trivalent inactivated vaccines only had 59% efficacy against flu in healthy adults.
The study comes amid debate over whether GPs who refuse vaccination are ‘selfish'. It highlights stark gaps in evidence for effectiveness in certain age groups, saying evidence in patients over 65 – one of the Department of Health's at-risk groups – is ‘lacking'. The study also raised concerns that protection against swine flu offered by vaccines was ‘not adequate' for pandemics, after finding a median effectiveness of 69% in people aged under 65.
Study leader Professor Michael Osterholm, director of the centre for infectious disease research and policy at the University of Minnesota, US, said: ‘Evidence for consistent high-level protection is elusive for the present generation of vaccines, especially in individuals at risk of complications or those aged 65 years or older. There is an urgent need for a new generation of more highly effective vaccines.'
Dr Margaret McCartney, a GP in Glasgow, said the study exposed the lack of ‘quality evidence' available on flu vaccination: 'The bottom line is we need better quality of evidence.'
‘Cochrane keeps telling us that. I'd like to be in a trial, but the DH seem to consider that it's too hard to do. That is at odds with work that has already been done.'
Lancet Infectious Diseases 2011, published online 26 October
