BACKGROUND AND AIMS: SARS-CoV-2 is a worldwide serious health problem and vaccination seems to have a crucial role in managing the COVID-19 pandemic. The aim of this prospective observational study was to monitor the trend of antibodies against SARS-CoV-2 after vaccination with BNT162b2 (COMIRNATY) in patients with inflammatory bowel disease treated by immunosuppressive and/or biological therapy, demonstrate whether any type of this therapy is associated with poorer production of antibodies against COVID-19 and evaluate the safety of vaccination against COVID-19 in these patients. METHODS: Eighty-seven eligible patients from one tertiary gastroenterological center with inflammatory bowel disease (60 with CD, 27 with UC) treated by immunosuppressive and/or biological therapy from the antiTNFα group were indicated to vaccination against SARS-CoV-2. Effectiveness of vaccination was evaluated by the values of antibodies before and 4 weeks after 2nd dose of vaccine. Additional goal was to evaluate adverse events of vaccination. RESULTS: Before the 2nd dose of vaccine, geometric mean of SARS-CoV-2 IgG antibodies were 40.7 U/ml in the biological therapy group, 34.8 U/ml in the azathioprine group and 44.8 U/ml in the combination therapy group of patients. The geometric means were 676.5.7 U/ml in the biological therapy group, 614.4 U/ml in the azathioprine group and 500.1 U/ml in the combination therapy group of patients four weeks after 2nd dose. Statistically significant differences between these groups were not proved. Several non-severe local and general adverse events were present in our patients with a majority of these events on the day of vaccine administration and the day after, no anaphylactic reactions were present. CONCLUSIONS: Our measurements proved the efficacy and safety of vaccination against SARS-CoV-2 in patients with inflammatory bowel disease treated by immunosuppressive and/or biological therapy. Statistically significant differences between our groups of patients were not proved.

1st Department of Infectious Diseases 2nd Medical Faculty Charles University Prague and Hospital Na Bulovce Prague Czech Republic

Department of Immunology 2nd Faculty of Medicine Charles University and Motol University Hospital Prague Czech Republic

Department of Internal Medicine 2nd Faculty of Medicine Charles University Prague and Motol University Hospital Prague Czech Republic

Department of Pediatric Surgery 2nd Faculty of Medicine Charles University Prague and University Hospital Motol Prague Czech Republic

Laboratory of Cellular and Molecular Immunology Institute of Microbiology of the Czech Academy of Sciences Prague Czech Republic

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