A new study published in the October 2007 Lancet (http://www.sciencedirect.com/science) by researchers at the National Institutes of Health (NIH), Bethesda, MD, concludes that influenza vaccinations in the US have prevented fewer deaths
than indicated by previous research (Arch Intern Med 2005; 165: 26572).
Previous research that compared death rates in vaccinated and unvaccinated groups of elderly people have shown that flu vaccination reduces all winter deaths by 50%. “But it’s really hard to find out who died of influenza because it’s not a reportable disease and few people are tested”, says lead NIH researcher Lone Simonsen. Some research has tested the efficacy of flu vaccines on illness but has not evaluated the effect of flu vaccines on influenza death rates in elderly people.
Over the past 25 years, the proportion of those aged 65 years or more who receive flu shots has climbed from 15% to 65% in the US. Previous research that compared death rates in vaccinated and unvaccinated groups of elderly people concluded that flu vaccination reduces all winter deaths by 50%. Yet current estimates of winter death causes suggest that flu-related mortality has actually risen since 1980.
Simonsen’s team took into account an aging population and the exceptional virulence of a flu strain prevalent in the 1990s. When her team analyzed the available data for causes of death in the elderly during the past 25 years, she says that about 10% of winter deaths could be
attributable to influenza, and more during the “pandemics” of the 1990s. The older study estimating 50% reduction of deaths in the winter was evidently “overestimating the mortality benefit of vaccination.” This is because the “endpoint” in these studies (death) wasn’t limited to death from the flu. Many winter deaths in the elderly are from pneumonia, and getting a flu shot would have no bearing on preventing death from pneumonia.
More older folks were getting flu shots, yet more of them were dying of the flu.Â It doesn’t add up.
Publication of Simonsen’s new study provoked strong reactions. The Centers for Disease Control and Prevention (CDC) reiterated its faith in existing studies, and questioned the methodology of the NIH study. Concerned by the impact of official disagreements on public confidence, the CDC
and NIH released a joint statement, saying that annual vaccinations continue to provide the best protection for elderly people.
Despite that official statement, other researchers, such as Dr. Ira Longini (Emory University, Atlanta, GA) maintains, “it is clear that increasing vaccination of the elderly has not resulted in a decrease in pneumonia and influenza mortality in that age group.” He points to a mix of robust
and frail immune systems in the population as an explanation for why some folks succumb to the flu, and why vaccination status doesn’t seem to matter. “As we increase vaccine coverage, a proportion of the elderly do not respond to vaccination and will get sick and die from flu whether they are vaccinated or not.”
Another way of saying this is: vaccinations may not impact death rates in the elderly at all. Further, given that the flu shot is still preserved with a mercury product (thimerosol), and that mercury toxicity has been linked to more rapid progression of Alzheimer’s in the elderly, one hopes that a future study will explore whether the elderly are actually better off without flu vaccines at all.