Breakthrough herpes zoster following recombinant zoster vaccinations in a rheumatoid arthritis patient receiving a Janus kinase inhibitor: A case report and literature review

The recombinant zoster vaccine (RZV) is immunologically and clinically effective in immunosuppressed patients. Though rheumatoid arthritis (RA) and the Janus kinase inhibitor (JAKi) increase the risk of herpes zoster (HZ) infection, breakthrough cases in which a HZ infection followed RZV administration are rare. We report herein a 63-year-old female patient with seropositive RA who experienced a HZ infection despite receiving the RZV. She had been receiving tocilizumab, methotrexate, and low-dose prednisolone until tocilizumab was switched to upadacitinib 4 weeks after two RZV administrations, which resulted in 63 weeks' remission. Her current admission was for a painful rash consisting of blisters and erythema on the right nasal alar and lips corresponding to the right V2 segment of the trigeminal nerve. HZ was diagnosed and treated for 7 days with intravenous acyclovir, which alleviated the symptoms. JAKi can suppress a range of immunogenic mechanisms which underlie the efficacy of the RZV. The present patient was expected to respond favourably to the RZV because JAKi had not been administered prior to the vaccinations; however, the later start of JAKi therapy caused a breakthrough HZ infection. Immunocompromised patients have a higher risk of severe HZ, including the disseminated form, but breakthrough cases are relatively rare. The RZV is recommended as prophylaxis against HZ as well as means of mitigating its severity when it does occur.