Fact Check: Covid Boosters Are NOT Weakening Immune System -- European Agency Says Remarks Were 'Misunderstood'

Fact Check

  • by: Ed Payne
Fact Check: Covid Boosters Are NOT Weakening Immune System -- European Agency Says Remarks Were 'Misunderstood'  Misunderstood

Are COVID-19 boosters weakening the immune system? No, that's not true: Articles and social media reports saying that Marco Cavaleri, the European Medicines Agency (EMA) vaccine strategy chief, fears repeated booster shots would weaken the immune system are incorrect. The EMA press office said, "It seems a journalist misunderstood the comments made by Dr. Cavaleri at the EMA's press briefing held [January 11, 2022], and as a result, unfortunately, published wrong information which was then relayed on social media and elsewhere."

In addition, the U.S. Food and Drug Administration (FDA) told Lead Stories there are no "safety signals regarding booster shots and immune response." Booster shots are recommended by the FDA and the Centers for Disease Control and Prevention.

The question appeared in a video from a Facebook post (archived here) published by Eric July on January 15, 2022, under the title "Boosters are weakening the immune system?" It opened:

We have yet to see the full ramifications just yet, but you're crazy if you think this is going off without a hitch.

This is what the post from the "For Canon Sake With Eric July" podcast looked like on January 18, 2022:

Eric July.png

Facebook screenshot(Source: Facebook screenshot taken on Tue Jan 18 15:42:08 2022 UTC)

The podcast is a response to comments made by EMA vaccine strategy chief Marco Cavaleri, who said at a press briefing on January 11, 2022, that there was no data yet supporting the need for a fourth COVID vaccine dose. A reporter then asked him why repeated boosters were not a long-term strategy. This was his response at 22:50 in the video:

Indeed, there are two concerns here that if we have a strategy in which we give boosters, let's say every four months approximately, we will end up, potentially, having problems with the immune response and the immune response may end up not being as good as we would like it to be. So, we should be careful in not overloading the immune system with repeated immunization. And secondly, of course, there is the risk of fatigue in the population with the continued administration of boosters.

In a January 18, 2022, email to Lead Stories, the EMA press office said it wanted to highlight two points from Cavaleri's comments:

  • Despite what some people have incorrectly reported, Dr Cavaleri has never said or implied that the repeated administration of boosters would weaken the immune system in any way. What he said is that repeated administration of boosters might lead to the immune response to the vaccine being lower, which means the vaccines could become less effective. This is because frequent and repeated immunisations with the same antigen could limit the maturation of the immune response possibly giving rise to a less than optimal immune response including memory cells.
  • Overall, as discussions and reflections are currently underway to shape the vaccination strategies going forward, Dr Cavaleri aimed to offer comment to explain the challenges around implementing a vaccination strategy which is based on repeated boosting (e.g. every 4 months) and the problems it can pose at different levels. In addition to the anticipated fatigue in the population, from a scientific point of view, repeated boosting is an approach where there is not much experience with other vaccines and, consequently, certain considerations need to be taken. Vaccination strategies moving forward will need to be carefully designed, with involvement of all relevant parties on a global scale and taking into account all new evidence which is constantly being generated.

The FDA also responded to Lead Stories in an email dated January 18, 2022:

The FDA is aware of the EMA report. To date, we have not seen any safety signals regarding booster shots and immune response. The FDA and CDC have robust safety and effectiveness surveillance systems in place to monitor COVID-19 vaccines authorized for emergency use in the U.S. The FDA is monitoring the safety of authorized COVID-19 vaccines through both passive and active safety surveillance systems. Additional information on the surveillance systems used may be found on FDA's web site: COVID-19 Vaccine Safety Surveillance | FDA.

In the United States, vaccination is recommended for everyone ages 5 years and older, according to the CDC website:

  • Hundreds of millions of people in the United States have received COVID-19 vaccines under the most intensive safety monitoring program in U.S. history.
  • A growing body of evidence shows that the benefits of COVID-19 vaccination outweigh the known and potential risks. CDC recommends an mRNA COVID-19 vaccine (Pfizer-BioNTech or Moderna) in most circumstances based on an updated risk-benefit analysis.

Booster shots are recommended for everyone 12 years and older, the CDC says. People should wait at least five months after completing their primary COVID vaccination series to get a booster, according to the agency.

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Lead Stories is working with the CoronaVirusFacts/DatosCoronaVirus Alliance, a coalition of more than 100 fact-checkers who are fighting misinformation related to the COVID-19 pandemic. Learn more about the alliance here.


  Ed Payne

Ed Payne is a staff writer at Lead Stories. He is an Emmy Award-winning journalist as part of CNN’s coverage of 9/11. Ed worked at CNN for nearly 24 years with the CNN Radio Network and CNN Digital. Most recently, he was a Digital Senior Producer for Gray Television’s Digital Content Center, the company’s digital news hub for 100+ TV stations. Ed also worked as a writer and editor for WebMD. In addition to his journalistic endeavors, Ed is the author of two children’s book series: “The Daily Rounds of a Hound” and “Vail’s Tales.” 

Read more about or contact Ed Payne

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