[Editor’s note: I’m sorry to do this twice in one month, but real life has intervened again and I have an urgent grant deadline tomorrow. As a result, I’m repurposing a post that some of you might have seen before in the last month. As always, if you don’t read my not-so-secret other blog, it’ll be new to you. If you do read that blog, I will reassure you that I did make some changes/updates so it’s not entirely a repost. It’s partially new to you. There will be all-new material next week, but I will warn you that I have two grants due, one on October 5 and one on October 6, which means that this might happen again for my October 5 post, although it’s not that likely, given that I have to upload my grant at least a business day—preferably two days—before the deadline. Also, I’ll try to arrange a guest post if I can’t get something together that week.]

The COVID-19 pandemic has now been going on for nine months, and it’s been six months since the first lockdowns were imposed in the US to slow the spread of SARS-CoV-2, the coronavirus responsible for the pandemic. Now we’re approaching the 2020-21 flu season, which threatens to make a bad situation even worse by adding another potentially lethal respiratory virus to the mix with SARS-CoV-2 and to confuse the care of severely ill patients with symptoms of respiratory infection, as doctors now have to consider the diagnostic possibility of seasonal influenza. Of course, antivaxxers have long targeted the flu vaccine because, compared to most other vaccines, it is an easier target. Different strains of flu predominate every year, forcing public health officials to make a “best guess” in the spring as to which influenza strains will dominate in the fall and winter, so that vaccines can be developed and manufactured in time. A consequence of this necessity is that the efficacy of the flu vaccine can vary widely from year to year. Mismatches between circulating flu strains and the vaccine can lead to poor efficacy some years, while during years that there is a good match to the circulating strains the efficacy is much better. Also, the response to the vaccine tends to be less robust in one group who most needs its protection, the elderly, although higher dose shots can partially solve that problem. Then there’s the issue that flu vaccine uptake is basically never sufficient to achieve community immunity in any given year. Even Mark Crislip used to concede that the flu vaccine is “suboptimal” but nonetheless argued that the evidence is sufficiently robust for its benefit to recommend it every year. Unfortunately, flu vaccines are only moderately effective, but it is clear that they are safe, and it should be remembered that influenza still kills, contrary to the claims of antivaxxers that the flu is not a serious illness.

With the arrival of the COVID-19 pandemic, it was not long before antivaxxers, being the conspiracy theorists that they are, latched onto a new conspiracy theory linking the flu vaccine to increased susceptibility to COVID-19. Indeed, the first I heard about this was in January, before the coronavirus and the disease it causes had even received their final, formal name. (That happened in March.) Back then, antivaxxers were blaming the flu vaccine for having sparked the COVID-19 outbreak in Wuhan, China that later spread to become a pandemic based on China’s having allegedly purchased more doses of flu vaccine than a usual year and a tenuous link to some science about viral interference that I’ll explain in a bit more depth in this post. I bring this up because a couple of weeks ago I came across an article on the website of Dr. Joe Mercola, the über-quack who’s built an online empire that’s made him worth over $100 million, asking “Might Flu Shots Increase COVID-19 Pandemic Risk?” The short answer is no. The long answer follows, and I consider it important to amplify my original rebuttal to this nonsense on a platform with several times more regular readers because antivaccine activists all across the quackosphere (like Robert F. Kennedy, Jr.) are parrotting the same claim as Mercola.

So the claim that the flu vaccine increases your risk of getting a life-threatening form of COVID-19, by 36% or by however much, is something I’ve written about at least twice already, once in January for my not-so-secret other blog and once in March for SBM. (Oh, wait, there was one other time.) So why revisit it? Simple. Flu season is upon us, which means that, pandemic or no pandemic, public health officials are rolling out the seasonal flu vaccine, as they do every year around this time. Indeed, I just got mine last week, and I had a really bad reaction to it. (Just kidding. I did have an adverse reaction, but it was nothing more than a sore shoulder for a couple of days, more sore than most years. It’s also here that I have to express the disappointment that I express nearly every year that my cancer center chose to use Fluarix Quadrivalent, which does not contain thimerosal. I almost asked the nurse administering the vaccine if she could add some extra thimerosal to it. OK, I’ll stop with the thimerosal jokes. At least the lack of thimerosal in Fluarix saved you from my older—and, I now realize, sometimes offensive to some—jokes when I did receive thimerosal containing vaccines about how the vaccine didn’t make me autistic.)

Of course, I don’t mind the yearly hassle. I get a flu vaccine every year and still remember the one time I didn’t twelve years ago and ended up knocked on my posterior for a week, sick as a dog with the flu. In any event, with the flu vaccine making its way to doctors’ offices, hospitals, and pharmacies near you, with public health messaging urging everyone to get vaccinated, it’s predictable that the antivaccine movement would do what the antivaccine movement always does at this time of year and try to convince people that the vaccine is dangerous. This year, more than even 2009-2010 (the year of the H1N1 influenza pandemic), this antivaccine pushback has the potential to be really dangerous. After all, with fall coming, there is a very real possibility of a resurgence of COVID-19 cases and deaths at the very same time that influenza cases will be increasing in the same way they do every year. We don’t have a vaccine against COVID-19 yet, but we do have one against influenza.

That’s why I decided to call out Mercola’s disinformation, which begins:

Could a “perfect storm” be brewing, ready to be unleashed this fall? If the regular influenza season ends up converging with a resurgence of SARS-CoV-2 outbreaks, or even a new SARS-CoV-3, the results are anyone’s guess at this point. Confounding matters is the possibility that influenza vaccination may increase people’s risk of other viral infections.

Mercola quotes Michael Osterholm, virologist and director of the Center for Infectious Disease Research and Policy at the University of Minnesota in Minneapolis, and Edward Belongia, director of the Center for Clinical Epidemiology and Population Health at the Marshfield Clinic Research Institute in Marshfield, who warned in an editorial in Science in June about the possibility of such a “perfect storm” of influenza and COVID-19 and urged an aggressive influenza vaccination campaign:

We do not yet have a COVID-19 vaccine, but safe and moderately effective influenza vaccines are available. Their widespread use is more important now than ever, and we encourage health care providers, employers, and community leaders to promote vaccination. Vaccine effectiveness varies by season and subtype, but vaccination offers similar protection against laboratory-confirmed influenza hospitalization and outpatient illness. Widespread misinformation on social media includes the false claim that influenza vaccination increases the risk of SARS-CoV-2 infection. Scientists, health care providers, and public health leaders must counter these claims with clear, evidence-based information on the importance of influenza vaccination during the COVID-19 pandemic.

It’s at this point that Mercola pulls a gambit that made me literally laugh out loud:

But this so-called “false claim” is not a rumor pulled out of thin air. As is so often the case, Osterholm and Belongia are actually insulting fellow virologists and researchers when slapping a hoax label on such claims, seeing how there is published research showing that, yes, influenza vaccination appears to worsen outcomes during viral pandemics.

If Osterholm and Belongia wanted to be factual and clear, they should dissect the actual studies using scientific methods and reasoning, and not just dismiss them as made-up internet hoaxes.

The fact that peer-reviewed studies have come to the conclusion that previous flu vaccination seems to increase patients’ risk of contracting more severe pandemic illness at least worthy of consideration and review.

You got that? By strongly refuting the unproven claim that influenza vaccination can increase the risk of COVID-19 and subsequent severe illness and death and characterizing it as “false”, Osterholm is insulting his fellow virologists and not listening to the science! Indeed, Mercola, amusingly, takes it one step further:

I’m not surprised though, seeing how Osterholm appears to routinely ignore the reality of published science. In a March 10, 2020, interview with Joe Rogan,2 in which the question of SARS-CoV-2’s origin came up, Osterholm stated that “we could not have crafted a virus like this to do what it’s doing; I mean we don’t have the creative imagination or the skill set.”

This simply does not line up with reality. Again, published research shows we clearly have the technology, know-how and “creative imagination” to create SARS-CoV-2.

Actually, Osterholm is correct. Although we have considerable expertise in genetic engineering and splicing genes in and out of viruses, it takes a lot more than that. In order to engineer something like SARS-CoV-2, you have to know enough about how coronaviruses cause disease and how they are transmitted and then about what structural features are required in the virus’ proteins to achieve the desired virulence and contagiousness, and we just don’t. Moreover, as I’ve pointed out many times before, once the complete nucleotide sequence of SARS-CoV-2 was elucidated, it became very clear that the virus was of natural origin. It had no tell-tale signs of having been engineered, as documented in a study in Nature in March. There’s just a lot of evidence that the virus was not engineered, but that doesn’t stop this conspiracy theory from popping up again and again, such as in Plandemic, the film featuring disgraced scientist Judy Mikovits and its sequel Plandemic: Indoctornation, or, as I like to call it, Plandemic 2: Electric Boogaloo.

Mercola bases his claim that the flu vaccine increases your risk of COVID-19 on five pieces of information. The last I’ll deal with first because it’s easy. I’ve already dealt with it before. Contrary to what Mercola claims, a 2020 study did not find that people were 36% more likely to get some form of coronavirus infection if they had been vaccinated against influenza. That claim is based on a gross misinterpretation of the study in question, plus a bit of misdirection. The study examined Department of Defense personnel from 2017-2018, long before SARS-CoV-2 emerged to cause the COVID-19 pandemic, meaning that the coronaviruses that the influenza virus allegedly interfered with in a phenomenon known as “viral interference”, the “interference” blocked by vaccination against the flu, were not SARS-CoV-2. Moreover, as I pointed out at the time, the study used to justify the “36%” claim was actually a negative study, with the coronavirus number cherry picked from a single table.

The rest of the studies that Mercola cites are, unsurprisingly, cherry picked and shoehorned into his narrative. First, there’s this:

So, what is the basis for these claims? Research raising serious questions about flu vaccinations and their impact on pandemic viral illnesses include a 2010 review3,4 in PLOS Medicine, led by Dr. Danuta Skowronski, a Canadian influenza expert with the Centre for Disease Control in British Columbia, which found the seasonal flu vaccine increased people’s risk of getting sick with pandemic H1N1 swine flu and resulted in more serious bouts of illness.

People who received the trivalent influenza vaccine during the 2008-2009 flu season were between 1.4 and 2.5 times more likely to get infected with pandemic H1N1 in the spring and summer of 2009 than those who did not get the seasonal flu vaccine.

The second study cited by Mercola is a study in ferrets that was presented at the 2012 Interscience Conference on Antimicrobial Agents and Chemotherapy. All Mercola could provide was a reference to a MedPage Today article. I wonder why, given that the actual study is easily locatable on PubMed, and I did locate it, where the authors conclude:

Although ferrets are considered the ideal animal model for human influenza infection, there are anticipated differences in immunologic and clinical aspects of immunization, infection and illness responses (timing, dosing and intensity) across species. Overall patterns may be compared but ferret studies do not support precise quantification of actual risk in humans. The greater likelihood of more severe disease based on several clinical indicators (weight loss, lung virus titers) among vaccinated compared to unvaccinated ferrets may not replicate the greater likelihood of medically-attended A(H1N1)pdm09 illness we previously reported in vaccinated humans.

Unsurprisingly, Mercola neglects to provide the appropriate level of uncertainty about this review article, as mentioned in this commentary by Marry McKenna:

But the authors warn that, since all four studies were observational, even careful design cannot rule out the possibility that some undetected methodologic bias affected the results. That caution is echoed in a companion editorial, written by US researchers unconnected to the Canadian study, who cite the contradictory results of six other studies conducted in Mexico, Australia, and the United States at the same time as the Canadian ones. Four of those studies found no association between seasonal flu vaccination and pandemic flu illness, while the two done in Mexico paradoxically found that seasonal flu shots may have had a protective effect.


“We have looked at our data at the CDC nationally,” Dr. Thomas Frieden, director of the CDC, said on Sept. 25, 2009. “I have looked carefully at the data from New York City where we had a very large outbreak and lots of information about what vaccine was received. The Australians have looked at it and published their information. And in none of those data is there any suggestion that the seasonal flu vaccine has any impact on your likelihood of getting H1N1. If data is published in the scientific literature, by all means, we would love to see it. If there’s preliminary data, we would love to see it. But nothing that we’ve seen suggests that that is likely to be a problem.”

Funny how Mercola neglected to mention this. What I was seeing at this point after the H1N1 pandemic was consistent with statistical noise. I was also amused to note that Danuta Skowronski also recently published a paper that found no increased risk of coronavirus or other non-influenza respiratory infection attributable to the influenza vaccine, thus refuting the “36%” claim Mercola parrots later in the article. (I also can’t resist mentioning this article that makes the case that selection bias is the reason for the apparent relationship between coronavirus diagnosis and the odds of prior influenza vaccination.)

Next up, Mercola picks more cherries:

Another study,7 published in the Journal of Virology in 2011, found the seasonal flu vaccine weakens children’s immune systems and increases their chances of getting sick from influenza viruses not included in the vaccine.

Further, when blood samples from 27 healthy, unvaccinated children and 14 children who had received an annual flu shot were compared, the former unvaccinated group was found to have naturally built up more antibodies across a wider variety of influenza strains compared to the latter vaccinated group, which is the type of situation Collignon referred to in the quote above.

Then there’s a 2012 study in the journal Clinical Infectious Diseases, which found that children receiving inactivated influenza vaccines had a 4.4 times higher relative risk of contracting noninfluenza respiratory virus infections in the nine months following their inoculation.

The authors proposed the theory that “Being protected against influenza, trivalent inactivated influenza vaccine recipients may lack temporary nonspecific immunity that protected against other respiratory viruses.”

First off, the first study did not find that the seasonal flu vaccine “weakens the immune system.” Immunologists don’t use terminology like “weaken” or “strengthen” the immune system. Second, this is a small study. Third, the study compared T-cell responses of normal children unvaccinated against the flu with children with cystic fibrosis who underwent yearly vaccination. That’s different from the way Mercola described it. It’s not clear if CF affected the results. The authors tried to argue that it did not, and maybe it didn’t, but we don’t know for sure because there was not the ideal control group, as the authors themselves acknowledged. Moreover, the finding reported is much more subtle than Mercola portrayed it. Basically, the finding was that a certain subset of T-cell response was less in the children vaccinated every year, but the authors noted that a live virus vaccine didn’t have that problem.

As for the second study cited, that’s a cherry picked study. As the CDC notes:

After that study was published, many experts looked into this issue further and conducted additional studies to see if the findings could be replicated. No other studies have found this effect. It’s not clear why this finding was detected in the one study, but the majority of evidence suggests that this is not a common or regular occurrence and that flu vaccination does not, in fact, make people more susceptible to other respiratory infections.

Maria Sundaram et al. (2013). Influenza Vaccination Is Not Associated With Detection of Noninfluenza Respiratory Viruses in Seasonal Studies of Influenza Vaccine Effectiveness.

Then Mercola throws a red herring in there to distract:

So, on the one hand, studies have shown that when you get the flu vaccine, you may become more prone to flu caused by influenza viruses that are not contained in the vaccine, or other noninfluenza viral respiratory illnesses, including coronavirus infections (more on that below).

Conversely, researchers recently found that common colds caused by the betacoronaviruses OC43 and HKU1 might actually make you more resistant to SARS-CoV-2 infection, and that the resulting immunity might last as long as 17 years.

The authors suggest that if you’ve beat a common cold caused by a OC43 or HKU1 betacoronavirus in the past, you may have a 50/50 chance of having defensive T-cells that can recognize and help defend against SARS-CoV-2.

This is, of course, good news if it’s true. If the finding is replicated, it would imply that many of us who get the common cold could also as a result have some immunity to COVID-19 without ever having had it. Of course, what Mercola is up to here is not reassurance. He’s using this example to suggest plausibility of his previous Gish galloping with cherry picked studies claiming that the flu vaccine increases your susceptibility to COVID-19, even though coronaviruses are very different from influenza viruses, meaning that having cross immunity between two coronaviruses does not necessarily imply the same relationship between flu viruses and coronaviruses like SARS-CoV-2.

Finally, Mercola pulls out a claim by someone named Dr. Michael Murry on Facebook dated March 30 that the flu vaccine resulted in a higher mortality among the elderly who contracted COVID-19:

Could a new flu vaccine be partly responsible for the COVID-19 mortality rate in Italy?In case you are not aware, the…

Posted by Dr. Michael Murray on Monday, March 30, 2020

Naturally, there is no scientific evidence presented to support this wild speculation. In addition, Dr. Vasquez runs a website called Inflammation Mastery and is, in addition to being a DO, a chiropractor and a naturopath. His website screams, “Quack!” It touts something called the “Functional Inflammation Protocol”, claiming brain inflammation is a cause of pain and fibromyalgia, and a book blaming autism on the “gut-brain axis”.

In the end, what we have here from “Dr.” Mercola is nothing more than a Gish gallop of cherry picked studies and observations without context designed to spread fear, uncertainty, and doubt about the flu vaccine. We also know that, despite extensive refutation online and in the mainstream media, the claim that influenza vaccines increase your risk of contracting COVID-19 by 36% (or by whatever) and increase your risk of dying from COVID-19 is yet another antivax slasher claim. What I mean by that is that this claim is like Jason Voorhees in the Friday the 13th movies or Michael Myers in the Halloween movies. No matter how many times you think he’s been killed at the end of one movie, he always returns for yet another sequel, and, when the sequels finally run out, there’ll always be a reboot of the series. Yes, conspiracy theories are the iconic hockey or William Shatner mask of the COVID-19/antivaxxer unholy alliance.

Mercola concludes with a warning about fast-tracked COVID-19 vaccines, which is a concern many of us on the provaccine side have brought up ourselves, thus providing the one bit of semi-reasonable concern sprinkled into the fear mongering, in order to provide a touch of plausibility. Also, there’s the grift. There’s always the grift, complete with a plug for an antivaccine conference in October by the National Vaccine Information Center, Barbara Loe Fisher’s antivaccine organization that Mercola has been generously supporting for over a decade.

Because of course there is.



Posted by David Gorski