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

Abstract

BACKGROUNDThe 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.AIMWe aimed to quantify the serological response to SARS-CoV-2 vaccines in those with IBD and determine antibody levels across varying therapeutic options.METHODSIndividuals with IBD who received first and/or second dose of a COVID-19 vaccine (Pfizer-BioNTech, Moderna, and/or AstraZeneca) were assessed for serological response (2–4 weeks after first dose; 2–8 weeks after second dose and 8–18 weeks after second dose) using the SARS-CoV-2 IgG II Quant assay to the spike protein of SARS-CoV-2. 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 ≥50 AU/mL. Secondarily, we evaluated the geometric mean titer (GMT) with 95% confidence intervals (CI).RESULTSTable 1 describes the characteristics of individuals with IBD (n=464) with serological data following the first dose (n=266) and/or second dose (n=303) of a COVID-19 vaccine. After the first dose of the vaccine, 81.6% seroconverted, with the lowest first-dose conversion rates in patients taking anti-TNF monotherapy (79.7%), anti-TNF combination therapy (52.9%), and corticosteroids (50.0%) (Table 1). Overall, 98.4% of the cohort seroconverted within 2–8 weeks of the second dose, with 94.6% seropositive within 8–18 weeks of the second dose. 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 (1679 AU/mL) to second dose at 2–8 week (7943 AU/mL) but fell significantly (<0.0001) to 3565 AU/mL 8–18 weeks from second dose (Table 1, Figure 1). GMT levels 2–8 weeks after second dose were higher in those with prior COVID-19 (12,729 AU/mL), but lower in those receiving anti-TNF combination therapy (4231 AU/mL) and oral corticosteroids (5996 AU/mL) (Table 1).CONCLUSIONSeroconversion 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 8 weeks post-full vaccination, which is consistent across medication classes.Table 1. Patient and vaccine characteristics, seroconversion rates, and geometric mean titres by prior PCR-confirmed COVID-19 status for each medication class.Figure 1. Log-transformed anti-SARS-CoV-2 spike antibody concentration per vaccine category. The wide black bar represents the median log antibody titre per vaccine category, while narrow black bars represent bounds of the interquartile range associated with each vaccine category. The solid blue line represents threshold for positive seroconversion [log10(50 AU/mL)].