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Mortality Benefits of Vaccine Programme for the Elderly Greatly Exaggerated

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The mortality beneï¬ ts of vaccinating elderly people against the inï¬'uenza virus have been greatly exaggerated, conclude authors of a Review published in the October edition of The Lancet Infectious Diseases.

Inï¬'uenza vaccination policy in most high income countries attempts to reduce the mortality burden of inï¬'uenza by targeting people aged at least 65 years for vaccination. Dr Lone Simonsen, George Washington University, Washington, DC, USA and colleagues say that frailty selection bias (ie, where not-so-frail elderly people are vaccinated more often than their inï¬ rm peers), and the use of non-speciï¬ c trial endpoints such as all-cause mortality have been the reasons behind this exaggeration. They say: "The remaining evidence base is currently insuï¬ cient to indicate the magnitude of the mortality beneï¬ t, if any, that elderly people derive from the vaccination programme."

The authors point out that although placebo-controlled randomised trials show the inï¬'uenza vaccine is eï¬ ective in younger adults, few trials have included elderly people, and especially those aged at least 70 years, the age-group that accounts for three-quarters of all inï¬'uenza related deaths. Such trials suggest that clinical beneï¬ ts and antibody responses in elderly people decline with increasing age past 70 years.

Further, they say that recent excess mortality studies have been unable to conï¬ rm a decline in inï¬'uenza-related mortality since 1980, even as vaccination coverage increased from 15% to 65%. The authors say: "Paradoxically, whereas those studies attribute about 5% of all winter deaths to inï¬'uenza, many cohort studies report a 50% reduction in the total risk of death in winter—a beneï¬ t ten times greater than the estimated inï¬'uenza mortality burden."

They propose that future trials should use more speciï¬ c endpoints, eg. vaccine eï¬ ectiveness against the highly speciï¬ c outcome of laboratory-conï¬ rmed inï¬'uenza virus, which although labour intensive and expensive, is more likely to obtain more realistic estimates of vaccine eï¬ cacy. Future trials should also identify the epidemic period for each season through use of actual virus surveillance data, rather than the current arbitrary four-month period.

They end with a note of caution, saying: "While awaiting an improved evidence base for inï¬'uenza vaccine mortality beneï¬ ts in elderly people, we suggest that this group should continue to be vaccinated against inï¬'uenza. Inï¬'uenza causes many deaths each year, and even a partly eï¬ ective vaccine would be better than no vaccine at all. But the evidence base concerning inï¬'uenza vaccine beneï¬ ts in elderly people does need to be strengthened."

In an accompanying Comment published Online in The Lancet today, Dr Tom Jeï¬ erson and Dr Carlo Di Pietrantonj, Cochrane Vaccines Field, Alessandria, Italy say: "If current evidence points to substantial uncertainty, then what next? Simonsen and colleagues suggest that 'refocusing on the likely complications of immune senescence would require vigorous pursuit of other options'. They also confront the ultimate taboo that drew so much scorn in the evidence overview: doing randomised trials in elderly people to settle the issue conclusively. That suggestion, which seems to ï¬'y in the face of current policies, is in our opinion the only ethical and scientiï¬ c way to have deï¬ nitive answer to the question of whether or not current inï¬'uenza vaccines protect elderly people."

Taken from The Lancet Infectious Diseases.

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