The influenza vaccine provides protection against the flu, but does not reduce mortality in the elderly, says a recent study in contradiction to earlier studies. The study in the Aug 2 issue of The Lancet by Canadian researchers, who evaluated data from patients admitted to six Capital Health hospitals in Alberta, indicates that the benefit of the vaccine was marginal.  

Study chief Dr. Sumit Majumdar of the University of Alberta in Edmonton, Canada explained in a statement, "The healthy-user effect is seen in what doctors often refer to as their 'good' patients -- patients who are well-informed about their health, who exercise regularly, do not smoke or have quit, drink only in moderation, watch what they eat, come in regularly for health maintenance visits and disease screenings, take their medications exactly as prescribed -- and quite religiously get vaccinated each year so as to stay healthy. Such attributes are almost impossible to capture in large scale studies using administrative databases."

Co-investigator Dr. Dean T. Eurich, who is also with the University of Alberta, added “Over the last two decades in the United Sates, even while (flu) vaccination rates among the elderly have increased from 15 to 65 percent, there has been no commensurate decrease in hospital admissions or all-cause mortality. Further, only about 10 percent of winter-time deaths in the United States are attributable to influenza, thus to suggest that the vaccine can reduce 50 percent of deaths from all causes is implausible in our opinion," he added.

In earlier studies a 50 % reduction in death from any cause had been noted for the elderly who had been given an influenza vaccine. "Previous studies were likely measuring a benefit not directly attributable to the vaccine itself, but something specific to the individuals who were vaccinated—a healthy-user benefit or frailty bias" said Eurich. The researchers also pointed out that though earlier studies have noted similar reductions in mortalities during the year when influenza viruses aren’t circulating. Apart from this is the fact that there have been no statistical differences between in-hospital mortality rates of elderly patients who received the flu vaccine and those who did not.

The researchers feel the findings of the study have broader implications for public health. Annual flu vaccines are a must for patients suffering from chronic diseases as well as their contacts.

Majumdar said, "But you also need to take care of yourself. Everyone can reduce their risk by taking simple precautions." The precautions mentioned were hand-washing, avoiding sick people during flu season, taking antiviral medication, and seeking prompt medical care. He said the findings should serve as a useful reminder for researchers, "The healthy-user effect is everywhere you don't want it to be."