The widely-held perception that the influenza vaccination reduces overall mortality risk in the elderly does not withstand careful scrutiny, according to researchers in Alberta. The vaccine does confer protection against specific strains of influenza, but its overall benefit appears to have been exaggerated by a number of observational studies that found a very large reduction in all-cause mortality among elderly patients who had been vaccinated.
The study included more than 700 matched elderly subjects, half of whom had taken the vaccine and half of whom had not. After controlling for a wealth of variables that were largely not considered or simply not available in previous studies that reported the mortality benefit, the researchers concluded that any such benefit “if present at all, was very small and statistically non-significant and may simply be a healthy-user artifact that they were unable to identify…”
“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,” said principal investigator Sumit Majumdar, M.D., M.P.H..
The finding has broad implications for patients, vaccine developers and for policy makers. You just may not need a flu vaccination unless there’s a specific flavor headed your way.
I’m one of those pain-in-the-butt healthy-user artifacts. Except for weight, I fit all the parameters. I usually get the flu shot each autumn.
And I probably will continue doing so. That’s what healthy users do.