Seroprevalence of SARS-CoV2 in IBD patients treated with biological therapy

Background and aims A similar course of COVID-19 in patients with inflammatory bowel diseases (IBD) and in the general population has been reported. However, disease prevalence in IBD patients is presently unknown. In this prospective observational study we aimed at determining SARS-CoV2 infection prevalence in IBD patients treated with biological therapy. Methods 354 sera from IBD patients under biological therapy recruited from three different locations in Italy and Germany were evaluated for antibody presence by RBD ELISA. Control groups were i) age-matched healthy subjects tested in the same time period in Milan, Italy; ii) healthy subjects collected in the pre-COVID era; iii) IBD patients under biological therapy collected in the pre-COVID era. Results 8 out of 354 patients tested positive for the anti-RBD-SARS-CoV2 IgG antibody (prevalence 2.3%). IgG positive patients’ percentage recruited from Milan was significantly higher than those recruited from other locations (prevalence 5.4% vs. 0.4% p < 0.005). IgG positive patients reported a significantly higher incidence of fever, anosmia and ageusia, and were more likely to have entered in close contact with COVID-19 positive subjects before the study enrolment. Conclusions Seroprevalence of SARS-CoV2 in IBD patients treated with biological therapy reflects values measured in the local general population. Specific symptoms and contact history with SARS-CoV2-infected individuals strongly increase the likelihood of SARS-CoV2 seropositivity.