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Home » mRNA COVID vaccines are not associated with appendicitis

mRNA COVID vaccines are not associated with appendicitis

I did not know it was a thing, but there were concerns that appendicitis was associated with mRNA COVID-19 vaccines from Moderna and Pfizer. Of course, I wanted to look into it and see if the link was supported by any published evidence because that’s what I do.

There was a safety signal for appendicitis that was first seen in Pfizer’s phase 3 clinical trial where a higher number of cases of appendicitis were observed. Some observations in Israel showed an “excess risk of appendicitis of 5.0 episodes per 100,000 individuals after vaccination.

However, a new study carefully examined new data and found no association between the mRNA COVID-19 vaccines and appendicitis. Let’s look at that study.

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The mRNA COVID-19 vaccines and appendicitis paper

In a paper published on 25 April 2022 in JAMA Internal Medicine, Helene Kildegaard, MD, of the University of Southern Denmark, and colleagues examined national Danish registry data on 4,048,883 participants who received COVID-19 mRNA vaccination and individuals who had a PCR-confirmed SARS-CoV-2 infection during Dec. 27, 2020, to Nov. 30, 2021. Most received the Pfizer-BioNTech vaccine for both doses. Those individuals with previous cases of appendicitis were excluded.

Here are some of the key results from the study:

  • Within 21 days of follow-up, 330 episodes of appendicitis occurred out of the 4,048,883 individuals who received the first dose (8.1 episodes per 100,000 vaccinated individuals). The rate of appendicitis after the second vaccine dose was slightly greater, with 340 cases among the 3,944,408 individuals who received it (8.6 episodes per 100,000 vaccinated individuals).
  • Those who were vaccinated did not have any significant risk of developing appendicitis within 21 days after the first (adjusted risk ratio [aRR] = 0.93) and second dose (aRR = 0.99). The lack of association between the vaccines and appendicitis remained stable regardless of gender, age, and which mRNA vaccine was received.
  • Furthermore, there was no significant risk of appendicitis after SARS-CoV-2 infection compared to the unvaccinated group (aRR = 1.25).

This supports an interim analysis published in JAMA that found no association between the mRNA vaccines and appendicitis.

woman suffering from a stomach pain
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I hang around many vaccine boards, and I have never seen anything about appendicitis. However, I know that if some anti-vaxxers saw the original data from the Pfizer clinical trial, they would try to tie the vaccines to appendicitis.

But this large study debunks any link between the two. You are not going to contract appendicitis by getting the vaccine. And it’s entirely possible that you could get appendicitis coincidentally after receiving the vaccine.


Michael Simpson

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