P626 SARS-CoV-2 seroprevalence in patients with Inflammatory Bowel Disease

García Mateo, S.(1,2);Martínez-Domínguez, S.J.(1,2);Aso Gonzalvo, M.C.(1);Gargallo-Puyuelo, C.J.(1,2,3);Gallego Llera, B.(1,2);Arroyo Villarino, M.T.(1,2,3);Laredo de la Torre, V.(1,2);Nocito Colon, M.M.L.(4);Lario Quilez, L.(1);Refaie, E.(5);Latre Santos, M.(3);Gomollón García, F.(1,2,3,6);

(1)Hospital Clínico Universitario "Lozano Blesa", Department of Gastroenterology, Zaragoza, Spain;(2)Aragón Health Research Institute, IIS Aragón, Zaragoza, Spain;(3)University of Zaragoza, School of Medicine, Zaragoza, Spain;(4)Hospital Clínico Universitario "Lozano Blesa", Department of Immunology, Zaragoza, Spain;(5)University of Milan, School of Medicine, Milan, Italy;(6)Centro de Investigación biomédica en red en el área enfermedades hepáticas y digestivas, CIBERehd, Zaragoza, Spain


Patients with Inflammatory Bowel Disease (IBD) suffer from a chronic illness and many of them need immunosuppressive therapy throughout the course of the disease.  Consequently, COVID-19 pandemic has caused uncertainty about the possible increased risk of suffering SARS-CoV-2 infection that could confer IBD or its treatments.

The aim of this study is to assess SARS-CoV-2 seroprevalence in patients with IBD as well as the existence of potential risk factors for its development.


This is a unicentric cross-sectional study developed in IBD unit of University Hospital “Lozano Blesa” of Zaragoza. Patients older than 18 years with established diagnosis of Crohn´s Disease (CD), Ulcerative Colitis (UC) or Indeterminate Colitis (IC) have been included. A blood sample has been drawn from each patient to detect IgG against SARS-CoV-2 (ELISA method) and each patient has completed a questionnaire to know symptoms related to infection and previous comorbidity. We have performed a descriptive analysis and a univariate analysis to study relationship between potential risk factors and seroconversion against SARS-CoV-2.


431 patients have been included, with a mean age of 50.2 ± 14.1 years and a 51.3% of women. Of them, 49.7% suffer from UC, 49.2% CD and 1.2% IC. Related to the treatment, 23.5% receive anti-TNF biologic agents, 13.1% other kind of biologic agents, 9.3% immunomodulators, 7.7% combined treatment (biologic agent and immunomodulator), 33.1% other treatment and 13.3% no treatment.

According to World Health Organization (WHO) definitions, 85.6% had not suffered the infection, 7.7% were confirmed cases (only 3 admitted patients) and 6.7% were probable cases. The seroprevalence of SARS-CoV-2 obtained is 8.8%, being significantly higher among confirmed cases than among probable cases (71.0% in confirmed vs 6.9% in probable; RR 10.3; p<0.001). A higher risk of seroconversion has been detected among patients without biologic agents (11.8% in patients without biologic agents vs 5.3% in patients with biologic agents; RR 2.2; p=0.021). No differences have been observed in the seroprevalence of patients with other treatments for IBD or in terms of age, active smoking, level of inflammation markers, the presence of symptoms of infection or hospital admission.


The seroprevalence of SARS-CoV-2 of Aragon´s patients with IBD is similar to that described in national seroprevalence study of Ministry of Health for the region (8.8%). The treatment with biologic agents is associated with a lower risk of seroconversion