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

Windsor JW, Caplan L, Ingram RJM, Charlton C, Kanji JN, Tipples G, Holodinsky JK, Bernstein CN, Mahoney DJ, Bernatsky S, Benchimol EI, Kaplan GG; STOP COVID-19 in IBD Research Group. Serological responses to the first four doses of SARS-CoV-2 vaccine in patients with inflammatory bowel disease. Lancet Gastroenterol Hepatol. 2022 Oct 25:S2468-1253(22)00340-5. DOI: 10.1016/S2468-1253(22)00340-5.

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 Lancet Gastroenterology & Hepatology by Drs. Gilaad Kaplan (University of Calgary) and Sasha Bernatsky (McGill University) on behalf of the STOP COVID-19 in IBD Research Group, showed a robust antibody response was achieved in individuals with IBD after the fourth dose of COVID-19 vaccine, similar in magnitude to that which followed the third dose. The research team also outlined predictors for vaccine-induced immune responses.

Key Findings:

  • Antibody titers increased significantly with each successive dose of vaccine, from the first to the fourth.
  • Each decade of increased age was associated with a decrease in the amounts of antibodies (antibody titers) post-vaccine dose 1, 2 and 3. For example, each decade of increased age was associated with a 12% decrease in anti-S (spike) antibody concentration after the third dose of vaccine.
  • People taking several types of drugs, including anti-TNF monotherapy, combination therapy, and corticosteroids, were associated with diminished anti-S concentrations compared to individuals not taking immunosuppressive medication. Corticosteroid use was associated with the lowest antibody titers across all medication classes. However, people with IBD who were taking these medications still showed significantly increased antibodies after third and fourth doses compared to after only two doses.
  • Antibody decay that was observed after the second dose (>8 weeks) and after the third dose (1–8 weeks) was restored following the fourth vaccine dose. Antibodies declined by 5% per week >8 weeks after the third dose.
  • A previous SARS-CoV-2 infection was significantly associated with increased anti-S concentrations demonstrating increased protection due to hybrid immunity.

The study results highlight the importance of each additional dose in maintaining humoral immunity. Individuals with IBD who are older than 65; people who require prednisone, anti-TNF, or combination therapies; and people with no previous SARS-CoV-2 infection have reduced antibody responses after three vaccine doses and are therefore most likely to benefit from a fourth dose. More research is needed to understand other immune responses to SARS-CoV-2 vaccination, including neutralizing antibodies or T-cell immunity, to help determine optimal vaccine dosing and dosing intervals.