The US Centers for Disease Control and Prevention (CDC) recommends that everyone aged six months and up, including pregnant women, get an annual influenza vaccine. The two fundamental assumptions underlying the CDC’s policy are that vaccination reduces transmission of the virus and reduces the risk of potentially deadly complications. Yet multiple reviews of the scientific literature have concluded that there is no good scientific evidence to support the CDC’s claims.
Notwithstanding the science, to increase demand for the pharmaceutical companies’ influenza vaccine products, the CDC makes use of fear marketing, asserting as fact that tens of thousands of people die each year from the flu, even though the CDC’s numbers actually estimate that are controversial because they are based on dubious assumptions that appear to result in a great overestimation of the negative impact of influenza on societal health.
The primary justification for the CDC’s flu vaccine policy is the assumption that it significantly reduces the mortality rate among people aged 65 and older, the group at highest risk of potentially deadly complications from the flu. The CDC declares to the public that the vaccine does so as though this was a scientifically proven fact. Yet, the reality is that the CDC’s bold claim that the vaccine greatly reduces the risk of death among the elderly has been thoroughly discredited by the scientific community.
… contrary to the CDC’s claims of a great beneficial effect on mortality, influenza mortality and hospitalization rates for older Americans significantly increased in the 80s and 90s, during the same time that influenza vaccination rates for elderly Americans dramatically increased.
The Implausibility of the CDC’s Claims
Concerns about the CDC’s mortality claim were raised by researchers from the National Institutes of Health (NIH) in a study published in April 2005 in Archives of Internal Medicine (now JAMA Internal Medicine). Their concern was prompted by the observation that, despite a considerable increase in vaccination coverage among people aged 65 or older—from at most 20 percent before 1980 to 65 percent in 2001—pneumonia and influenza mortality rates had actually substantially risen.
That is to say, to quote a review published in Virology Journal in 2008, contrary to the CDC’s claims of a great beneficial effect on mortality, “influenza mortality and hospitalization rates for older Americans significantly increased in the 80s and 90s, during the same time that influenza vaccination rates for elderly Americans dramatically increased.” (Emphasis added.)
As the authors of the 2005 NIH study commented, this result was “surprising” since vaccination was supposed to be “highly effective at reducing influenza-related mortality”—an assumption underlying CDC policy that “has never been studied in clinical trials”.
Relying instead on post-marketing observational studies of the general population, the CDC has claimed that vaccine efficacy in preventing influenza-related deaths is as high as 80 percent. Furthermore, to support its claim of an enormous benefit, the CDC has relied on a meta-analysis of observational studies that concluded that vaccination reduces the number of flu-season deaths from any cause among the elderly “by an astonishing 50%.”
In their own study, however, the NIH researchers found that, over the course of thirty-three flu seasons, influenza-related deaths were on average only about 5 percent and “always less than 10% of the total number of winter deaths among the elderly.”
The obvious question was: How could it be possible for the influenza vaccine to reduce by halfdeaths during winter from any cause when no more than one-tenth of deaths in any given flu season could be attributed to influenza?
The most obvious answer was that it couldn’t, and so the researchers examined more closely the methodology of the observational studies that the CDC was relying upon. The conclusion they drew from doing so was that the CDC’s implausible numbers were due to a systemic bias in those studies. There was a “disparity among vaccination” in these studies between cohorts that received a flu vaccine and those that didn’t.
Specifically, it wasn’t that vaccinated individuals were less likely to die, but that sick elderly people whose frail condition made them more likely to die during the coming flu season were less likely to get a flu shot.
Faced with this identification of a systemic bias in their methodology and despite the obvious implausibility of its own claims, the CDC’s response was to question the methodology of the NIH researchers’ study while reiterating its unshaken faith in the studies it was relying upon to promote the flu vaccine.