Viral infections and complications in inflammatory bowel disease

This thesis aimed to clarify the impact of several viral infections, their complications and vaccination responses in patients with inflammatory bowel disease (IBD). The first part focuses on two herpes viruses, Epstein-Barr virus (EBV) and cytomegalovirus (CMV), that can cause severe opportunistic infections, mostly as a rare complication of the use of immunosuppressants. In the second part we studied the risk of the premalignant condition cervical intraepithelial neoplasia (CIN) and cervical cancer caused by human papillomavirus (HPV) in women with IBD and we aimed to identify risk factors, in particular by studying the exposure to immunosuppressants in detail. The third part describes an uncommon case of a hepatitis E virus (HEV) infection in a patient using the gut-selective biologic agent vedolizumab. In the last part of this thesis, we focused on vaccination responses to influenza vaccination and severe acute respiratory coronavirus 2 (SARS-Cov-2) vaccination in immunocompromised patients with IBD and other immune-mediated inflammatory diseases (IMID).