Varicella-zoster virus (VZV) is one of the eight herpesviruses that infect humans by manifesting as varicella. After primary infection VZV remains latent for life. In 30% of individuals the virus reactivates causing a secondary infection, herpes zoster (HZ). The most common complication of HZ is post-herpetic neuralgia (PHN) and, in severe cases, disseminated infection and death. The incidence of HZ increases as cell-mediated immunity (CMI) declines due to advanced age or the administration of immunomodulatory or immunosuppressive therapies. With the approval of the recombinant adjuvanted glycoprotein E (gE) vaccine (RZV; Shingrix™, GSK) also in immunocompromised individuals (IC) HZ is now considered a vaccine preventable disease. The development of novel biologic therapies has revolutionized the treatment of inflammatory skin conditions improving clinical responses in psoriasis and psoriatic arthritis patients. Although the overall safety records of biologic therapies are outstanding, there is evidence of an increased risk of contracting viral infections by nature of their inherent immunomodulatory and immunosuppressive effects.
Primary myelofibrosis (MF) is a myeloproliferative neoplasm. The development and approval of ruxolitinib, the first JAK1/2 inhibitor indicated to treat MF, has improved patient outcomes and overall survival. However, JAK inhibitors also suppressed the immune system impairing Natural Killer cell function and virus-specific T cell response. These may potentially result in increased infections (and in particular of VZV reactivation).
Given the increased risk of HZ associated with immunomodulant therapy, data on the immunogenicity and safety of RZV in IC populations are urgently needed.