THE RECENT REPORTS of Takahashi and his associates1-6 in Japan on the effectiveness and innocuity of a live, attenuated varicella-zoster virus vaccine call for an examination of the nature and magnitude of the disease problem to be prevented and of the other factors on which a decision to use such a vaccine must be based.
The virus that causes chickenpox (varicella) and its sequela, herpes zoster, is one of the most contagious viruses and sooner or later infects everyone in the world. Primary infection usually results in the typical disease that varies in severity from a mild febrile illness with its characteristic vesicular eruption, to a more severe disease with pneumonia, encephalopathy, encephalitis, a variety of other complications, and occasionally, death. If the data reported for 1952 to 1961 in Massachusetts7 apply currently for the entire United States, 90.5% of the primary disease occurs in children under 10