Published 3 September 2008, doi:10.1136/bmj.a1550
Cite this as: BMJ 2008;337:a1550

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Bias alone could account for benefit attributed to flu vaccine, study finds

Jeanne Lenzer

1 New York

The first 150 words of the full text of this article appear below.

The reduction in mortality seen among elderly people who have been given the flu vaccine could have more to do with a "healthy user" effect than any protective value of the vaccine itself, a study has found.

The researchers, from the University of Alberta in Edmonton, Canada, prospectively obtained clinical, laboratory, and functional status data and identified 1813 adults with community acquired pneumonia who were admitted to six hospitals in Alberta (American Journal of Respiratory and Critical Care Medicine 2008;178:527-33, doi:10.1164/rccm.200802-282OC). Of these adults, 354 vaccine recipients met the inclusion criteria and were matched with 354 controls.

The outcome of in-hospital mortality was examined during the months before and after the flu season, when no benefit of the flu jab would be expected.

The researchers replicated a 51% mortality difference between the groups found in previous observational studies (JAMA 1994;272:1661-5): 53 (15%) of the vaccinated control . . . [Full text of this article]


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