LAUSR

s of the 16th Congress of ECCO European Crohn’s and Colitis Organisation S381 Background: Given that IBD patients were excluded from COVID-19 vaccine trials, there is a lack of vaccine efficacy data in this population. In this study, we evaluated longitudinal serological responses to SARSCoV-2 infection as well as to COVID-19 vaccination in IBD patients. Methods: We collected clinical data and sera from IBD patients enrolled in an observational SARS-CoV-2 sero-surveillance study at our large hospital center in New York City during routine infusions and clinic visits. To distinguish between infection and vaccination, sera was collected prior to vaccination where possible, and all sera was tested for both antibodies to SARS-CoV-2-specific RBD, the target of current available vaccines in the U.S., and nucleocapsid proteins. Results: Our results reveal waning antibody titres in 13 of 16 (81%) patients infected with SARS-CoV-2 over a course of 6-7 months. Of 48 vaccinated patients, 16 patients completed vaccine schedules with two doses, and all 16 (100%) achieved seroconversion above the threshold required for convalescent plasma donation. Conclusion: While antibody responses to infection in IBD patients have questionable stability, completion of the COVID-19 vaccine series in IBD patients results in robust serological responses. To our knowledge is the first data confirming adequate serological responses to COVID19 vaccination in IBD patients with and without biologic medications. Studies are needed to assess adequacy of dosing schedules, medication effects, measurement of cell-mediated responses, durability of immune responses, and clinical efficacy of COVID-19 vaccines in IBD patients.