A seroepidemiological study of Varicella-Zoster virus in Taipei City

Varicella has been considered a common and benign disease of children. However, adults tend to have severe disease and in some high risk groups, such as neonates and leukemic patients, varicella infection can be fatal. A large-scale seroepidemiological study on varicella was performed to reveal the current varicella infection status and to serve as a prevaccination survey before the possible implementation of vaccination program in Taiwan. This study included a total of 1384 individuals whose ages ranged from newborns to old adults. Enzyme-linked immunosorbent assay was adopted to determine the IgG antibodies against Varicella-Zoster virus. The results showed: (1) only 24% of infants aged birth to three months had maternal antibodies, (2) the seroprevalence increased slowly during the first 3 years after birth, (3) most infections occurred between 3 and 10 years old, (4) 10% (female) to 20% (male) of adults were still susceptible to varicella infection, and (5) 85% of pregnant women had antibodies against VZV. These data suggest that if varicella vaccination is to be done in Taiwan, the appropriate inoculation age would be between 12 and 24 months. Besides, there exists a pool of uninfected adults who potentially will develop severe illnesses once infected and should be screened and protected by varicella vaccines.