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 it really was a thing.
Apparently, 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. There were also some observations in Israel that showed an “excess risk of appendicitis of 5.0 episodes per 100,000 individuals after vaccination.
However, a new study carefully looked at new data and found no association between the mRNA COVID-19 vaccines and appendicitis. Let’s look at that study.
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.
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 “null association” 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).
I hang around a lot of vaccine boards, and I have never seen anything about appendicitis. However, I know that if some anti-vaxxer saw the original data from the Pfizer clinical trial, they will try to tie the vaccines to appendicitis.
But this large study debunks any linke 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.
- Kildegaard H, Ladebo L, Andersen JH, Jensen PB, Rasmussen L, Damkier P, Pottegård A. Risk of Appendicitis After mRNA COVID-19 Vaccination in a Danish Population. JAMA Intern Med. 2022 Apr 25. doi: 10.1001/jamainternmed.2022.1222. Epub ahead of print. PMID: 35467699.
- Klein NP, Lewis N, Goddard K, Fireman B, Zerbo O, Hanson KE, Donahue JG, Kharbanda EO, Naleway A, Nelson JC, Xu S, Yih WK, Glanz JM, Williams JTB, Hambidge SJ, Lewin BJ, Shimabukuro TT, DeStefano F, Weintraub ES. Surveillance for Adverse Events After COVID-19 mRNA Vaccination. JAMA. 2021 Oct 12;326(14):1390-1399. doi: 10.1001/jama.2021.15072. PMID: 34477808; PMCID: PMC8511971.
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