Immunogenicity of BNT162b2 Vaccine in Patients with Inflammatory Bowel Disease on Infliximab Combination Therapy: A Multicenter Prospective Study

Shehab, M.; Abu-farha, M.; Alrashed, F.; Alfadhli, A.; AlOtaibi, K.; Alsahli, A.; Thanaraj, T. A.; Channanath, A.; Ali, H.; Abubaker, J.; Al-Mulla, F.

Background Vaccination is a promising strategy to protect vulnerable groups like inflammatory bowel disease (IBD) patients against COVID-19 and associated severe outcomes. COVID-19 Vaccines clinical trials excluded IBD patients taking infliximab with azathioprine or 6-mercaptopurine (infliximab combination). Therefore, we sought to evaluate serologic responses to COVID-19 vaccination with the mRNA vaccine, BNT162b2 in IBD patients receiving infliximab combination therapy compared to healthy participants. Methods This is a multicenter prospective study. IBD patients were recruited at the time of attendance at infusion center between August 1st, 2021, and September 15th, 2021. Our primary outcome was the concentrations of SARS-CoV-2 antibodies 4-10 weeks after vaccination with two doses of BNT162b2 vaccine in IBD patients taking infliximab combination therapy (study group) compared to healthy participants group (control group). Both study and healthy participants groups were matched for age, sex and time-since-last-vaccine-dose using optimal pair matching method. Results In total 116 participants were recruited in the study, 58 patients in the study group and 58 in the control group. Median (IQR) IgG concentrations were lower in the study group [99 BAU/mL (40, 177)] than the control group [139 BAU/mL (120, 188)], following vaccination (p = 0.0032). Neutralizing antibodies was also lower in the study group compared to the control group [64% (23, 94) vs 91% (85, 94), p <0.001]. The median IgA levels in the study group was also significantly lower when compared to the control group [6 U/ml (3, 34) vs 13 U/ml (7, 30), p =0.0097]. In the study group, the percentage of patients who achieved positive IgG, neutralizing antibody and IgA levels were 81%, 75% and 40% respectively. In the control group, all participants (100%) had positive IgG and neutralizing antibody levels while 62% had positive IgA levels. Conclusion In patients with IBD receiving infliximab combination therapy, IgG, IgA and neutralizing antibody levels after BNT162b2 vaccine were lower compared to healthy participants. However, most patients treated with infliximab combination therapy seroconverted after two doses of the vaccine.