This is a summary, written by members of the CITF Secretariat, of:

Markovinović A, Quan J, Herauf M, Hracs L, Windsor JW, Sharifi N, Coward S, Caplan L, Gorospe J, Ernest-Suarez K, Ma C, Panaccione R, Ingram RJM, Kanji JN, Tipples G, Holodinsky JK, Bernstein CN, Mahoney DJ, Bernatsky S, Benchimol EI, Kaplan GG; STOP COVID-19 in IBD Research Group. Adverse Events & Serological Responses Following SARS-CoV-2 Vaccination in Individuals with Inflammatory Bowel Disease. Am J Gastroenterol. 2023 May 22. doi: 10.14309/ajg.0000000000002337.

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

A CITF-funded study, published in The American Journal of Gastroenterology, found that SARS-CoV-2 vaccines are safe for those with inflammatory bowel disease (IBD). Injection site reactions were the most common adverse event, most common after earlier doses, but when following a 4th dose, they were significantly associated with increased antibody levels. The study was led by Dr. Gilaad Kaplan (University of Calgary) in collaboration with Dr. Sasha Bernatsky (McGill University Health Centre) on behalf of the STOP COVID-19 in IBD Research Group.

Key findings:

  • Severe adverse events in people with IBDs were rare, occurring in 0.03% of cases.
  • None of the study participants had an IBD flare within 30 days of vaccination.
  • Adverse event reporting was highest after the 1st (83.5%) and 2nd doses (80.1%), compared to the 3rd (77.0%) and 4th doses (67.7%).
  • Injection site reactions (ISRs) were the most common adverse event. They occurred less frequently following a 4th dose (56.3%), compared to other doses (70.9%-76.9%).
  • Injection site reactions were significantly more frequent among:
    • People under 65 years-old after the 1st, 2nd, and 3rd doses
    • Females after 1st and 2nd doses
    • Participants who received the Pfizer vaccine after 2nd
  • ISRs were significantly associated with increased antibody levels following a 4th dose, but not earlier doses.

Participants with IBD were interviewed using the adverse events following immunization (AEFI) form to capture any adverse events within 30 days of the 1st, 2nd, 3rd, and/or 4th dose of monovalent mRNA SARS-CoV-2 vaccine. Participants were interviewed in October 2021 to assess adverse events for the first three doses and then in May 2022 for the 4th dose. A total of 316 participants received <3 doses; 187 received 3 doses, and 96 received 4 doses. Adverse events were defined as those occurring within 30 days of vaccination and without an alternative cause. Severe adverse events were defined as those attributable to the vaccine and necessitating a visit to the emergency department or admission to the hospital, and/or participants who did not fully recover by the time of the interview. Participants who self-reported worsening gastrointestinal symptoms following vaccination were identified as having a potential IBD flare.


In summary, this study affirms the safety of SARS-CoV-2 monovalent mRNA vaccines in IBD.