MODIFIED VARICELLA-LIKE SYNDROME

After incidental exposure to natural varicella, up to 18% of vaccinees reported a breakthrough infection known as modified varicella-like sy ndrome (MVLS) over up to 10 years of postvaccination follow-up, compar ed with natural varicella occurring in similarly aged unvaccinated chi ldren at the rate of 9% per year. Children with MVLS are frequently as ymptomatic, and their disease is characterized by having fewer lesions , less fever, and lasting fewer days than natural varicella. When a ca se of MVLS occurs there are few secondary cases, suggesting that it is infrequently transmitted. Sequelae such as secondary bacterial infect ion, cerebellar ataxia, encephalitis, and pneumonia occur infrequently .