Epidemiological characteristics and serological survey of mumps 15 years after MMR vaccine was included in the immunization program.

Mumps is a vaccine-preventable acute viral infectious disease. To understand the incidence of mumps and population immunity in Quzhou City after measles mumps rubella vaccine (MMR) was included in the immunization program, we analyzed the epidemiological characteristics of mumps cases from 2009 to 2023 and a cross-sectional serosurvey of IgG antibodies to mumps conducted in 2024. We found that 15 years after the MMR vaccine was included in the immunization program, the incidence of mumps was significantly reduced in all populations, but the incidence remained highest in vaccinated children aged 0-12 years. Vaccine escape may explain the high incidence of mumps in highly vaccinated populations. Updating vaccines or developing a new vaccine that targets multiple viral genotypes may be necessary to improve the effectiveness of the vaccine against infection and fully control infections and outbreaks. The positive rate and concentration of mumps IgG antibody were inconsistent with the incidence data. mumps IgG antibody is not an ideal substitute for immunity and cannot be used to accurately predict whether a target population is susceptible or protected. Natural infections may provide longer-lasting immunity than vaccination.