Efficacy
Few immunocompromised or immunosuppressed patients were included in the vaccine clinical trials. However, there is a theoretical risk of sub-optimal vaccine response in these patients as some of the medications commonly used in IBD are known to reduce response to non-COVID vaccinations. Patients on high dose steroids (>20mg prednisolone) have impaired antibody development in response to vaccines and anti-TNF therapy has been shown to impair immunogenicity following influenza, pneumococcal and hepatitis B vaccination. Conversely vedolizumab, a gut specific anti-integrin, does not impair vaccine response.
While we await real-life data regarding vaccine efficacy for preventing symptomatic and severe COVID-19 infection in IBD patients, there are two recent studies examining antibody response in IBD patients on biologic medications:
- CLARITY IBD study reported antibody response and seroconversion rates in 865 infliximab treated patients who received either Pfizer-BioNTech or AstraZeneca vaccines
- Infliximab was associated with attenuated immunogenicity to a single dose of vaccine but most achieved seroconversion after second dose
- Antibody response was reduced in older patients and smokers
- ICARUS-IBD study evaluated responses to vaccination with mRNA vaccines (Pfizer-BioNTech and NIH-Moderna) in 48 IBD patients
- Reported 100% seropositivity following 2 x doses of vaccination in IBD patients on biological therapy
- In patients with previous SARS-COV2 seroconversion a single dose of either vaccine induced high antibodies
These results are relatively reassuring and support COVID-19 vaccination in this group though highlight the importance of ensuring the patient receives both the first and second vaccine dose.
Safety
Limited data but there are no specific safety concerns anticipated beyond those of general population. There is currently no data on risk of thrombosis with thrombocytopaenia syndrome following vaccination with AstraZeneca vaccine in IBD patients. Vaccines do not appear to be associated with risk of flare of IBD.
Timing of vaccination
No specific data but current recommendation is to avoid vaccination on the same day as a regular biologic infusion to avoid incorrect attribution of vaccine-related adverse events to the infusion treatment or vice versa. Vaccination should not be delayed due to scheduled biologic dose and biologic dose should not be delayed due to vaccine.
Summary of recommendations
- COVID-19 vaccination recommended in IBD patients
- Seroconversion rates are high in IBD patients on biologics who receive both doses of vaccine. Do not delay 2nd dose of vaccine.
- High dose steroids may impair vaccine response so recommend delaying vaccine until weaned to <20mg prednisolone or equivalent assuming community risk of COVID-19 remains low
- No vaccine brand preference between Pfizer and AstraZeneca beyond general ATAGI recommendations
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Article by Dr Claire Gordon
Dr Claire Gordon is a gastroenterologist with a subspecialty interest in luminal gastroenterology, particularly inflammatory bowel disease. She is interested in the management of complex inflammatory bowel disease, aiming to achieve mucosal healing and optimise patients’ quality of life.
Click here to read more about Dr Claire Gordon
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