SEROLOGICAL RESPONSES TO SARS-COV-2 VACCINATION IN PATIENTS WITH INFLAMMATORY BOWEL DISEASE: A PROSPECTIVE COHORT STUDY

ABSTRACT

Background: The immune response of SARS-CoV-2 vaccines is uncertain in those with Inflammatory Bowel Disease (IBD) due to a diverse array of immune-modifying therapies that vary in the mechanism of immunosuppression. Aim: We aimed to quantify the serological response to SARS-CoV-2 vaccines in those with IBD and determine antibody levels across varying therapeutic options. Methods: Individuals with IBD who received a first and/or second dose of a COVID-19 vaccine (Pfizer-BioNTech, Moderna, and/or AstraZeneca) were assessed for serological response (1–8 weeks after first dose;1–8 weeks after second dose, 8–18 weeks after second dose, 18+ weeks after second dose) using the SARS-CoV-2 IgG II Quant assay to the receptor-binding domain of the SARS-CoV-2 spike protein. The cohort was stratified based on age, sex, vaccine received, IBD type, IBD therapeutic, and prior confirmed diagnosis of COVID-19. The primary outcome was seroconversion defined as IgG levels of ³50 AU/mL. Secondarily, we evaluated the geometric mean titer (GMT) with 95% confidence intervals (CI). Results: Table 1 describes the characteristics of individuals with IBD (n=466) with serological data following the first dose (n=247) and/or second dose (n=413) of a COVID-19 vaccine. After 1–8 weeks following first dose of the vaccine, 81.4% seroconverted, with the lowest first-dose conversion rates in patients taking anti- TNF monotherapy (80.3%), anti-TNF combination therapy (51.5%), and corticosteroids (50.0%) (Table 1). Overall, 98.4% of the cohort seroconverted within 1–8 weeks of the second dose. Over time, seropositive rates decreased with 95.8% seroconversion within 8– 18 weeks of the second dose and 90.5% after 18 weeks. Seroconversion after second dose was consistently high across all medication classes (range 94.6%–100.0%), except for oral corticosteroids (62.5%). GMT levels significantly increased (p<0.0001) from first dose (1825 AU/mL [95% CI 981, 2668 AU/mL]) to second dose at 1–8 week (9059 AU/mL [7698, 10420 AU/mL]) but fell significantly (p<0.0001) to 3649 AU/mL (95% CI 2562, 4736 AU/ mL) 8–18 weeks from second dose and 2527 AU/mL (95% CI 883, 4172 AU/mL) 18+ weeks after second dose (Table 1, Figure 1). GMT levels 1–8 weeks after second dose were higher in those with prior COVID-19 (16,770 AU/mL), but lower in those receiving anti- TNF combination therapy (4231 AU/mL) and oral corticosteroids (5996 AU/mL) (Table 1). Conclusion: Seroconversion rates following full-regimen vaccination are high in patients with inflammatory bowel disease across all medication classes except for anti-TNF combination therapy and oral corticosteroids. Antibody titres and seroconversion rates tend to decrease after eight weeks post-full vaccination, which is consistent across medication classes. (Table Presented) Table 1. Patient and vaccine characteristics, seroconversion rates, and geometric mean titres by prior PCR-confirmed COVID-19 status for each medication class. (Figure Presented) Figure 1. Log-transformed anti-SARS-CoV-2 spike antibody concentration per vaccine category. Black points represent GMTs while narrow black bars represent bounds of 95% CI associated with each GMT. Solid blue line represents threshold for positive seroconversion [ln (50 AU/mL)].