Review Article: vaccination for patients with inflammatory bowel disease during the COVID-19 pandemic

Abstract

Background: Poor immune responses are frequently observed in patients with inflammatory bowel disease (IBD) receiving established vaccines; risk factors include immunosuppressants and active disease.

Aims: To summarise available information regarding immune responses achieved in patients with IBD receiving established vaccines. Using this information, to identify risk factors in the IBD population related to poor vaccine-induced immunity that may be applicable to vaccines against COVID-19.

Methods: We undertook a literature review on immunity to currently recommended vaccines for patients with IBD and to COVID-19 vaccines and summarised the relevant literature.

Results: Patients with IBD have reduced immune responses following vaccination compared to the general population. Factors including the use of immunomodulators and anti-TNF agents reduce response rates. Patients with IBD should be vaccinated against COVID-19 at the earliest opportunity as recommended by International Advisory Committees, and vaccination should not be deferred because a patient is receiving immune-modifying therapies. Antibody titres to COVID-19 vaccines appear to be reduced in patients receiving anti-TNF therapy, especially in combination with immunomodulators after one vaccination. Therefore, we should optimise any established risk factors that could impact response to vaccination in patients with IBD before vaccination.

Conclusions: Ideally, patients with IBD should be vaccinated at the earliest opportunity against COVID-19. Patients should be in remission and, if possible, have their corticosteroid dose minimised before vaccination. Further research is required to determine the impact of different biologics on vaccine response to COVID-19 and the potential for booster vaccines or heterologous prime-boost vaccinations in the IBD population.

FIGURE 1

Impact of having IBD and IBD medications on the immune response to COVID‐19 vaccines. A, Innate immune priming: IBD is associated with SNPs in genes regulating the innate immune response (eg innate immune sensors such as TLRs), therefore tissue resident antigen presenting cells (eg DCs) in patients with IBD may respond differently to the vaccines. Inflammatory cytokines produced in response to the vaccines may be blunted by anti‐inflammatory medications (eg corticosteroids or biologic agents such as anti‐TNF). B, Antigen presentation: Mature DC migrate to the local LN where they present antigen to naïve CD4/CD8+ T and B lymphocytes, providing co‐stimulation and driving polarisation by secreting cytokines. IBD medications can limit antigen presentation. C, T cell proliferation and polarisation: Patients with CD tend to have immune responses polarised towards inflammatory Th1/Th17 cells, while patients with UC have a bias towards Th2 cells. D, CD4+ T cell: B cell interaction: Antigen specific CD4+ T cells interact with B cells providing co‐stimulation via CD40:CD40L interaction to drive B cell proliferation, affinity maturation and class switch recombination. T cell‐derived cytokines (eg IL‐4) are key to determining the antibody isotype and function. E, Immune Memory: Antigen‐specific T and B cell clones expanded due to vaccination should give rise to long‐lived memory cells. Patients with IBD frequently display an exhausted T cell phenotype (due to constant immune activation) and this may impact the phenotype and function of immune memory cells. Image created by BioRender.com.