Varicella-zoster virus infection in rheumatoid arthritis patients in the anti-tumour necrosis factor era

Patients with rheumatoid arthritis are increasingly being treated with different drugs (both non-biologic and biologic disease-modifying anti-rheumatic drugs - DMARDs) that may have immunomodulatory, cytotoxic, or immunosuppressive effects; in particular, anti-tumour necrosis factor (TNF) agents are raising major concern as regards safety issues. An increased risk of infections has been extensively reported during anti-TNF treatment, owing to the primary role of TNF in host defense and immune responses. Although in clinical practice cases of reactivation of varicella zoster virus (VZV) infections during therapy with TNF inhibitors commonly occur, the knowledge on this topic deriving from randomised clinical trials is limited. In this narrative review we focus on the pathophysiology of VZV infection and the role of TNF, and report the available data about VZV outbreaks recorded on Registries of rheumatic patients treated with anti-TNF agents. Finally, we discuss screening strategies and promising preventive measures against VZV infection.