Objective  To examine influencing and long-term protective effect of two doses of mumps containing vaccine (MuCV) on mumps incidence in vaccinated children and to provide references for optimizing the two-dose MuCV immunization program.

  Methods  Immunization records and mumps morbidity data were collected among the children born during 2003 – 2016 received two doses of MuCV in Yantian district of Shenzhen city. Cox regression analysis was used to analyze the influencing factors of mumps and the effectiveness of MuCV vaccination.

  Results  Among the 8 451 children included in the study, totally 146 mumps incidents were reported, with an incidence rate of 1.73%. Of the children, 35.86% had the first dose of MuCV at the age of 8-month and 46.25% had the second dose at ages of 2 – 3 years; only 5.64% had the second dose at 4 – 6 years old. The shortest time between two doses of MuCV was 28 days and the longest was 164 months, with a median of 11 months. The main type of MuCV used for the first dose was measles-mumps vaccine (59.58%) and the second dose was measles-mumps-rubella vaccine (55.32%). Cox regression analysis indicated that the time period between two doses of MuCV was significantly correlated with the risk of mumps (P = 0.033). The risk of mumps was reduced by 43.2% (odds ratio = 0.568, 95% confidence interval: 0.382 – 0.845) for the children with the time period of 13 – 36 months between the two dose of MuCV compared to those with the time period of less than 12 months. Kaplan-Meier survival analysis showed that the average protective period of the two doses of MuCV against mumps was 95 – 176 months.

  Conclusion  The study results suggest that the first and the second dose of MuCV should be administered in the children aged 18 months and 3 – 4 years and the time interval between the two doses should be 13 – 36 months for the control of mumps epidemic effectively in the region.