Varicella Vaccination: a Potential Strategy for Preventing Multiple Sclerosis

Multiple sclerosis (MS) is a debilitating neurological condition affecting approximately 2.9 million people worldwide. Its cause remains unclear but environmental factors, such as post-childhood Epstein-Barr virus (EBV) infection, are thought to contribute to MS incidence. This study presents a new hypothesis that MS may be initiated by primary infection with clade 3 varicella-zoster virus (VZV) preceding primary EBV infection. The hypothesis may explain several MS epidemiological features: geographic variation in prevalence, changes in incidence and sex ratios over time, migration patterns, higher EBV and VZV seropositivity rates in patients versus healthy controls, extremely high MS rates in Sardinia, and identification of clade 3 VZV in a single MS patient. If validated, the hypothesis predicts exclusive detection of clade 3 VZV in MS patients, declining MS incidence in countries implementing universal childhood varicella vaccination since the early 2000s, and potential therapeutic benefits for existing MS patients from treatments that prevent herpesvirus reactivation.