Altered lymphocyte profiles and herpes zoster infections in patients with multiple sclerosis on natalizumab.

Cases of herpes zoster (HZ) in patients with MS on natalizumab (NTZ) have been documented. In this study, we assessed lymphocyte subsets in NTZ-treated patients with HZ compared to matched controls without HZ. Twenty unvaccinated patients developed HZ while on NTZ for an incidence rate of 12.3 per 1000 patient-years. These patients had lower CD8+% and higher CD4+:CD8+ ratios (p ⩽ 0.01) than non-HZ matched controls. Two patients with relapsing-remitting MS developed HZ twice while on NTZ. These findings underscore the importance of pre-NTZ HZ vaccination due to potential HZ risk.