Debunking Denialism

Defending science against the forces of irrationality.

Anti-Vaccine Misinformation about the Seasonal Influenza Vaccine

Related: Mike Adams and The Deadly Doctor Gambit, Mainstream Climate Science Defeats Global Crank Mike Adams.

Natural News spreads misinformation about seasonal influenza vaccine

Natural News is perhaps the largest website devoted to the promotion of quack treatments for almost any medical condition and anti-scientific falsehoods. They spread a massive amount of misinformation on a wide range of topics such as climate change, genetically modified foods, water fluoridation, vaccines and advocate conspiracy theories about contrails, aspartame, antidepressants and even about the 2012 Aurora shooting. Its founder, Mike Adams, have been discussed on this website before when he attempted to dismiss the harmful consequences of global warming by parroting the same tired old denialist falsehoods about the fertilization effect and coral bleaching. He also attempts to argue that doctors are more dangerous than guns (a pseudoscientific argument called the deadly doctor gambit), apparently without taking into account the enormous benefit that modern medicine brings.

Recently, the Natural News website published a post written by Ethan A. Hoff that is spreading pseudoscientific misinformation about the seasonal influenza vaccine. He falsely claim that the efficacy of the inactivated seasonal influenza vaccine is just 1.5%, when in reality, it is close to 60%. He denies that over 200 000 people become hospitalized from influenza-related complications and blames that on the vaccine instead. He also fearmongers about the side-effects when they are most often fairy mild. Finally, there is no consistent evidence that vitamin D, garlic or any of the other “natural health” products that Hoff promotes can prevent influenza infection.

Effectiveness of influenza vaccine is around 60%

According to a meta-analysis of influenza-vaccine efficacy carried out by Osterholm, Kelley, Sommer and Belongia (2012), the pooled efficacy of the trivalent inactivated vaccine in adults between the ages of 18 and 65 were 59% with a 95% confidence interval stretching from 51% to 67%. This is a fairy good efficacy considering that too few people get the vaccine to establish herd immunity and that health authorities like the WHO and CDC has to reason under some uncertainty as to which vaccine strain should be included each year. It is not a perfect vaccine by any means, but still medically important.

Hoff repeats Mike Adams misinterpretation of these results when he asserts that the efficacy of the influenza vaccine is only 1.5%. As it turns out, this is the difference between the proportion of individuals who are vaccinated who get the influenza (1.2%) and the proportion of individuals who are not vaccinated who get the influenza (2.7%). However, such a comparison is misleading. Gorski (2011), in response to the original post by Adams, points out that:

Does Adams know that pretty much the same can be said of any preventative measure? The vast majority of people will not get the disease protected against by whatever modality, be it a vaccine, a drug, or–yes–a supplement or dietary intervention of the sort that Mike Adams promotes on his website. All preventative measures, be they vaccines, dietary or lifestyle interventions, or whatever, involve having a large number of people undergo them knowing that on an absolute basis few will actually benefit. That’s why risk-benefit ratios become so important. For the flu vaccine the risk is very, very low indeed, which is one reason why vaccination against this disease makes sense.

In other words, the absolute risk reduction is misleading in this case and the more important statistic to look at is the relative risk reduction (and the overarching comparison between benefit and risk). Gorski continues:

Adams uses absolute benefit numbers rather than relative risk reduction numbers in order to try to make the benefit of flu vaccination seem negligible. However, small absolute numbers, on a percentage basis, can easily represent large numbers of people when applied to populations. For example, there are estimated to be around 312 million people in the U.S. as of the 2010 census, of which approximately 235 million are adults aged 18 and over. If 2.7% of those adults get the flu every year, that’s roughly 6.3 million cases of flu every year. Preventing 60% of those cases translates to preventing 3.8 million cases of the flu every year. That’s nothing to sneeze at, if you’ll excuse my choice of phrasing. Of course, I know that nowhere near 100% of American adults are vaccinated against the flu every year, but even if only 50% were the number of cases prevented would still be huge.

In essence, Adams do not grasp medical statistics and Hoff ignorantly repeats Adams misunderstanding.

Deaths and hospitalizations from influenza-related complications are very real

Over 200 000 people are hospitalized each year in the U. S. due to influenza-related complications and between 4000 and ~50 000 influenza-related deaths have occurred per year between 1976 and 2006 (CDC, 2011; CDC, 2013a; Thompson et al., 2004).

Hoff outright denies these figures and claim that hospitalizations and deaths from influenza-related complications are “actually attributable to pneumonia”, apparently not understanding that pneumonia is a complication of influenza infection. Instead, he claims that the influenza-related cases of pneumonia is just the “result of a severely compromised immune system” and “the flu shot itself”. In reality, pneumonia is not a documented side-effect of the influenza vaccine (CDC, 2013b).

Side-effects of seasonal influenza vaccination are often mild

CDC (2013b) covers the possible side-effects of seasonal influenza vaccination. These are often mild, including swelling at the site of injection, coughs, fever, aches, itching and fatigue. Moderate side-effects include increased risk of febrile seizures for children simultaneously getting the seasonal influenza vaccine and the pneumococcal vaccine. Established severe side-effects include a ~1 in 1 million risk of a severe allergic reaction (this same risk occurs with most vaccines). There is also a conjectured possibility that there is a ~1-2 in 1 million risk of Guillain-Barré Syndrome, but this has not been established by sufficient scientific evidence (Immunization Safety Review, 2003).

Hoff claims that the seasonal influenza vaccine cause dementia. However, a study published by Verreault and colleagues (2001) showed that getting vaccines against influenza was associated with a reduced risk of developing Alzheimer’s. Another study, Voordouw et al. (2004) showed that getting an influenza vaccine was associated with a lower overall risk of dying from all causes. The claim that the seasonal influenza vaccine cause dementia was put forward by Hugh Fudenberg (an associate of Andrew Wakefield), an American medical doctor who got his license suspended by South Carolina Board of Medical Examiners back in 1995 (Gorski, 2007; Deer, 2011). His argument was presumably based on a correlation fallacy: elderly individuals are more likely to get dementia than younger people in the first place independently of vaccination status.

Hoff also repeated the thimerosal gambit, despite the fact that published scientific research and major scientific and medical associations have found this preservative to be safe. Hoff also fail to mention that it is only used for some multi-dose preparations of the inactivated seasonal influenza vaccine and that single-dose preparations and the attenuated seasonal influenza vaccine does not used thimerosal whatsoever. Here is how CDC (2013c) explain the situation:

What is thimerosal?

Thimerosal is a mercury-based preservative that has been used for decades in the United States in multi-dose vials (vials containing more than one dose) of some vaccines to prevent the growth of germs, bacteria and fungi, that can contaminate them.


Do the 2013-2014 seasonal flu vaccines contain thimerosal?

The Food and Drug Administration (FDA) has approved several formulations of the seasonal flu vaccine, including multi-dose vials and single-dose units. (See Table of Approved Influenza Vaccines for the U.S. 2013–2014 Season.) Since seasonal influenza vaccine is produced in large quantities for annual immunization campaigns, some of the vaccine is produced in multi-dose vials, and contains thimerosal to safeguard against possible contamination of the vial once it is opened.

The single-dose units are made without thimerosal as a preservative because they are intended to be opened and used only once. Additionally, the live-attenuated version of the vaccine (the nasal spray vaccine), is produced in single-dose units and does not contain thimerosal.


Is thimerosal in vaccines safe?

Yes. There is a large body of scientific evidence on the safety of thimerosal. Data from several studies show the low doses of thimerosal in vaccines do not cause harm, and are only associated with minor local injection site reactions like redness and swelling at the injection site.

Three U.S. health agencies (The Centers for Disease Control and Prevention (CDC), the Food and Drug Administration (FDA), and the National Institutes of Health (NIH)) have reviewed the published research on thimerosal and found it to be a safe product to use in vaccines. Three independent organizations [The National Academy of Sciences’ Institute of Medicine, Advisory Committee on Immunization Practices (ACIP), and the American Academy of Pediatrics (AAP)] reviewed the published research and also found thimerosal to be a safe product to use in vaccines. The medical community supports the use of thimerosal in influenza vaccines to protect against potential bacterial contamination of multi-dose vials.

Curiously, Hoff claims that side-effects of the seasonal influenza vaccine includes “flu-like symptoms” and that this “defeats the point” of getting vaccinated in the first place. While some mild side-effects of the seasonal influenza vaccine might be classified as influenza-like, such as coughs and fever, this does not defeat the point of getting vaccinated because you do not risk influenza-complications like pneumonia and you also cannot spread this symptoms to others since you are not actually infected.

Vitamin D and alleged “superfoods” do not prevent influenza infection

Contrary to Hoff, there is not enough evidence to conclude that vitamin D prevents influenza infection and certainly not that it does a better job than influenza vaccines (Hall, 2010). A report from Institute of Medicine (2011, pp. 181-182) puts it like this:

However, even though animal models indicate plausibility for a mechanistic role for vitamin D in autoimmune or anti-microbial function, results from RCTs as well as from observational associations between vitamin D and calcium and risk for either autoimmune or infectious diseases show a lack of consistency. Although both retrospective and prospective studies tend to support an inverse association between serum 25OHD levels and autoimmune and infectious diseases, these studies are limited in their interpretation owing to confounding effects that require further verification. The evidence available from RCTs is of limited utility because of the small size of the trials, inconsistency in measured outcomes, and lack of dose–response data. Overall, the evidence was not consistently supportive of a causal role for vitamin D combined with calcium or for vitamin D alone in reducing risk for developing auto-immune or infectious diseases. In the absence of verifiable dose–response data from RCTs a conclusion about asthma, autoimmune, or infectious diseases as indicators for DRI development cannot be reached.

Similarly, the University of Maryland medical center (2013) states that there is not sufficient evidence to conclude that Spirulina or garlic can prevent influenza infection. No credible evidence was presented for the notion that unspecified medical mushrooms prevent influenza infection either.


The efficacy of the inactivated influenza vaccine is close to 60% and not 1.5% that Hoff claims. Despite his denials, there are over 200 000 hospitalizations per year of influenza-related complications, including pneumonia and several tens of thousands of people die each year. The side-effects of influenza vaccination are often mild and it does not increase the risk of dementia. There is not sufficient evidence to establish that vitamin D, Spirulina, garlic or medical mushrooms can prevent influenza infection. This is yet another case of ignorant claims about vaccines from the anti-science advocates at Natural News.


CDC. (2011). Seasonal Influenza-Associated Hospitalizations in the United States. Accessed: 2013-09-28.

CDC. (2013a). Seasonal Influenza. Accessed: 2013-09-28.

CDC. (2013b). Possible Side-effects from Vaccines. Accessed: 2013-09-28.

CDC. (2013c). Thimerosal and 2013-2014 Seasonal Flu Vaccines. Accessed: 2013-09-28.

Deer, Brian. (2011). How the vaccine crisis was meant to make money. BMJ, 342.

Gorski, D. (2007). Bill Maher: Antivaccination Wingnut. Accessed: 2013-09-28.

Gorski, D. (2011). Mike Adams vs. the flu vaccine. Respectful Insolence. Accessed: 2013-09-28.

Hall, H. (2010). New Recommendations for Calcium and Vitamin D Intake. Accessed: 2013-09-28.

Institute of Medicine. (2011). Dietary Reference Intakes for Calcium and Vitamin D. Washington D. C.: The National Academies Press.

Thompson W.W., Shay D.K., Weintraub E., et al. (2004). Influenza-Associated Hospitalizations in the United States. JAMA. 292(11):1333-1340.

University of Maryland Medical Center (2013). Influenza. Accessed: 2013-09-28.

Verreault, René, Laurin, Danielle, Lindsay, Joan, & Serres, Gaston De. (2001). Past exposure to vaccines and subsequent risk of Alzheimer’s disease. Canadian Medical Association Journal, 165(11), 1495-1498.

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