Our study analyzes the association between the varicella incidence and serum antibody level in the post-vaccine era. We retrieved and analyzed the incidence and prevalence data for children age 1–14 years in Wenzhou, China. A cross-sectional seroepidemiology analysis was carried out in a series of 168 general healthy children aged 1–14 years and children at a varicella outbreak in Wenzhou. Our data showed a significant surge in the incidence and prevalence of varicella in children aged 10–14 years while they were kept relatively stable. The seroepidemiological analysis revealed a 7.3-fold significantly higher level of serum varicella IgG in healthy control students exposed at the outbreak than that in generally healthy children. The children 10–14 years old had the lowest rate of second-dose vaccination among the three age classes, and children 5–9 years old who received the second dose had a higher level of serum protective IgG than those who did not. The findings from the present study warn a two-dose vaccine schedule to reduce the climbing incidence and prevalence observed in the older children and suggest a higher serum IgG threshold for adequate protection of children from the varicella outbreak.
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