Varicella (VarV) vaccine is not included in Chinese national immunization schedules but 2- dose VarV (VarV2) has been recommended since 2014 in Hangzhou for children 1 to 4 years of age. The observed increase in VarV2 vaccine efficacy (VE) differs greatly from one study to another.

The China Disease Control and Prevention Information System reports on all cases of varicella found in Hangzhou hospital (CISDCP). On 31 January 2020, demographic details on the occurrence of confirmed varicella cases were retrieved from CISDCP. The study carried out a 1:1 case-control analysis to evaluate VarV efficacy. Standardized questionnaires were used for collecting participant data. The Hangzhou Immunization Information System has reviewed the status of VarV vaccination (HZIIS).

The occurrence of varicella was measured annually in 2019 to be 120 per 100,000 populations. The reported average varicella prevalence was high in particular in people between the ages of 10 and 19 and in suburbs. VarV immunization provided a high degree of varicella security, while VE of VarV2 improved.

A 2-dose VarV approach is strongly advised and appropriate health institutions should consider including VarV in the national immunization program for improved control and varicello burden reduction.