Viral replication and immunologic responses in children naturally infected with varicella-zoster virus and in varicella vaccine recipients.

Replication of varicella-zoster virus (VZV) and immunologic responses to VZV were examined by a sensitive culture technique for viral isolation and standard immunologic assays in children after close exposure to wild-type VZV or after inoculation with strain Oka varicella vaccine. Naturally infected children who developed clinical varicella had viremia between five days before and one day after clinical onset of disease, with the highest isolation rate one and two days before onset, and seroconversion followed two days later. Virus was not isolated from blood 12 and 13 days after contact in subclinically infected children. In the vaccine recipients a positive skin test reaction to VZV was observed as early as four to five days after immunization, and antibody appeared later. Virus was not isolated from blood and throat of the vaccinees from three to 14 days after immunization.