Influence of immunization schedule adjustment on mumps antibody level in healthy population based on an immunity level surveillance results in Hunan, 2020−2022

Objective To understand the influence of immunization schedule adjustment on mumps antibody level in healthy population in Hunan province and provide evidence for the evaluation of short-term immunization effect of 2-dose mumps containing vaccine (MuCV).

Methods A mumps immunity level surveillance in healthy population was conducted in Hunan from January 2020 to December 2022. In local children aged 1-3 years, those who got 2 dose MuCV vaccination after immunization schedule adjustment were selected as 2-dose group and those who only got 1 dose MuCV vaccination were selected as 1-dose group. The positive rate and geometric mean concentration (GMC) of mumps IgG in two groups were calculated and compared.

Results A total of 169 study subjects were included, including 73 in 2-dose group and 96 in 1-dose group. There was no significant difference in gender, age, and interval from last MuCV vaccination between two groups (χ²=0.002, P=0.963; χ²=3.618, P=0.164; χ²=0.757, P=0.685). The positive rate of mumps IgG was higher in 2-dose group (98.63%) than in 1-dose group (81.65%) (χ²=12.553, P<0.05). The GMC of mumps IgG was higher in 2-dose group (928.48 IU/mL) than in 1-dose group (265.89 IU/mL) (H=47.659, P<0.05).

Conclusions The positive rate and GMC of mumps IgG increased in 1–3 years-old healthy population after the implementation of 2-dose MuCV vaccination in Hunan, and the GMC of IgG showed no obvious decline in the observation period, but the influences of immunization schedule adjustment on long-term immunity persistence and reduction of mumps cases need to be further observed.