Fact Check

Did the Flu Shot Cause This Year's Flu Epidemic?

This claim is based on the incorrect interpretation of single quote from one nurse in Wisconsin who, for the record, recommends getting the shot.

Published Feb 14, 2018

Updated Feb 14, 2018
Article 3 of 10 in Collection
Production of the flu shot caused the influenza virus to mutate into a more virulent strain, driving the deadly 2017-2018 flu season.

On 8 February 2018, Erin Elizabeth, the founder of the reality-adjacent website “Health Nut News,” published an article claiming that a public health official had stated her belief that this year’s flu epidemic was the result of a virus mutated by the production of influenza vaccines.

Her piece, which inexplicably carried the headline “ABC: Experts Say Flu Shot Potentially Caused the Flu Epidemic” despite not once mentioning or citing ABC News in its text, rested solely on a single quote from a Burnett County, Wisconsin, nurse which was found in an article published by the local newspaper the Burnett County Sentinel (described repeatedly in Elizabeth's piece as an example of “the mainstream media”):

While part of the blame lies with the dominant flu strain this year, H3N2, which tends to be more severe and causes more severe symptoms than most other strains, it also potentially lies with us:

“I believe that the low effective rate of the vaccine this year is due to the mutations that the virus made in the processing of the vaccine itself,” said Anna Treague, nurse for Public Health. “That is at LEAST part of the reason that influenza cases are so widespread this year.”

Elizabeth’s article strongly suggests that she believes the nurse intended this statement to imply that the H3N2 virus is a mega-bug created as a result of the production of a vaccine against it. This interpretation, however, represents a full-scale misunderstanding of the vaccine manufacturing process and is likely (though our request for comment from Treague has not been returned) a misrepresentation of what the nurse was trying to convey.

To understand the confusion, it helps to know how the flu shot is typically manufactured. The most common process for the influenza vaccine is what the CDC terms an “egg-based manufacturing process.” Under this method, strains of influenza are injected into chicken eggs that sustain the virus, allowing it to proliferate and incubate before the antigens (chemicals formed by the virus that produce an immune response) produced in the egg are harvested:

The egg-based production process begins with CDC or another laboratory partner ... providing private sector manufacturers with candidate vaccine viruses (CVVs) grown in eggs per current FDA regulatory requirements. These CVVs are then injected into fertilized hen’s eggs and incubated for several days to allow the viruses to replicate. The virus-containing fluid is harvested from the eggs. For flu shots, the influenza viruses for the vaccine are then inactivated (killed), and virus antigen is purified.

As we explained in a debunker of another Elizabeth post just one month ago, a leading hypothesis for why vaccination against H3N2 (the most virulent strain this season) is so ineffective is that during the fertilized egg portion of the production process, the virus may mutate at a faster rate in (or it may react differently to) the egg matrix in which it is grown. As described in a January 2018 New England Journal of Medicine perspective piece, many studies have demonstrated that H3N2 can adapt itself to the conditions of the (avian) egg, resulting in the creation of antigens (and therefore vaccines) that have little or no effect on humans:

Another factor that may alter the effectiveness of influenza vaccines is the substrate used to produce them. In the United States, most influenza-vaccine viruses are propagated in eggs ... During the egg-based production process, the vaccine virus acquires amino acid changes that facilitate replication in eggs ... Since the influenza [hemagglutinin, HA] is the primary target of neutralizing antibodies, small modifications in this protein can cause antigenic changes in the virus and decrease vaccine effectiveness.

Egg adaptation has been postulated to contribute to low vaccine effectiveness, particularly with influenza A (H3N2) viruses; however, the true impact is largely unknown.

This means that, as Treague stated, a plausible reason discussed in the medical literature regarding the flu shot’s ineffectiveness “is due to the mutations that the virus made in the processing of the vaccine itself.” What this does not mean, however, is that a mutated superbug was created by humans, as suggested by Elizabeth. The problem is not that a new virus has been created that cannot be controlled; the problem is that the virus changed slightly while in the egg, producing a harvest of irrelevant antigens for vaccine production.

The notion that a virus can mutate, while perhaps scary sounding, is far from revelatory. All strains of the influenza virus are in a constant state of relatively rapid mutation — this is why the flu shot changes every year based on the predictions of scientists monitoring the prevalence and drift of flu strains around the world.

Elizabeth then goes on to suggest that, despite having to hunt for a vague quote in an obscure local paper to make her case, that “other experts agree”:

The Health Department official says it’s at LEAST part of the problem, if not the whole problem, and other experts agree. Dr Mercola (his video is below), who has had the #1 health site -- worldwide -- for 20 years, agrees, “It’s no surprise at all”, he says. We have countless other MDs and PhDs who concur as well. As doctors continue to give the dangerous shot and the virus mutates, more people will get sick and the epidemic will worsen. It’s like a bad sci-fi movie.

The primary expert she cites is Dr. Mercola, who -- outside of being fined or warned by the FTC and FDA for making unsubstantiated or misleading medical claims -- is Elizabeth’s partner. His views are well outside the mainstream, are oftentimes poorly researched and erroneous, and are strongly motivated by his anti-vaccine readership.

Regardless, the premise of a “bad sci-fi movie” epidemic caused by vaccine production gone wrong is based on a willfully misleading or grossly incorrect interpretation of a vague quote highlighted to scare readers and generate clicks, not illuminate the issue. The notion that humans caused the most problematic strain in this year’s flu season is not only incorrect, it is not even what the nurse’s quote is likely suggesting. Another quote from the nurse in the Burnett County Sentinel story is less difficult to misconstrue:

If you are able, get the flu shot. Even if the flu vaccine isn’t as effective as it has been in year’s past it does help. Some protection is better than no protection.

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Elizabeth, Erin.   “ABC: Experts Say Flu Shot Potentially Caused the Flu Epidemic (Shocker, In Mainstream No Less).”     Health Nut News.   8 February 2018.

Richie, Jonathan.   “Influenza Potentially Made Stronger by Vaccines.”     Burnett County Sentinel.   8 February 2018.

Centers for Disease Control and Prevention.   "How Influenza (Flu) Vaccines Are Made.”     Accessed 14 February 2017.

Paules, Catharine I. et al.   “Chasing Seasonal Influenza — The Need for a Universal Influenza Vaccine.”     New England Journal of Medicine.   4 January 2018.

Wu, Nicholas, C. et al.   “A Structural Explanation for the Low Effectiveness of the Seasonal Influenza H3N2 Vaccine.”     PLOS Pathogens.   23 October 2017.

Russell, Colin A. et al.   “Influenza Vaccine Strain Selection and Recent Studies on the Global Migration of Seasonal Influenza Viruses.”     PLOS Pathogens.   23 October 2017.

Groopman, Jerome.   “There’s No Way Out of It!”     New York Review of Books.   5 March 2015.


Correction [14 February 2018]: An earlier version of this story incorrectly stated that antibodies are produced during the vaccine production process. In fact, the egg manufacturing process creates antigens, not antibodies.

Alex Kasprak is an investigative journalist and science writer reporting on scientific misinformation, online fraud, and financial crime.