Mumps antibody in the Thai population 17 years after the universal measles mumps rubella vaccination program

Abstract

Introduction: mumps vaccination implementation in the form of MMR – measles, mumps, and rubella) in Thailand for first-grade school students since 1997 and for infants 9–12 months of age since 2010 resulted in a dramatic decline in the incidence of and deaths from mumps. However, there has been a resurgence of mumps outbreaks in Thailand, even in vaccinated populations.

Methodology: We aimed to determine the current seroprevalence of IgG antibodies to mumps in those 0–60 years of age from four different geographic areas of Thailand, and compare the results with our previous serosurvey in 2004.

Results: Seropositivity rates in children 0–7 years of age increased significantly from 45.8% in 2004 to 72.3% in 2014 after the launch of the MMR vaccine for infants. In the 8–14-year age group who had received one dose of mumps vaccination, the seropositivity rate was 66.7%. In the 15–19-year age group the seropositivity rate was the lowest, at 52.5%.

Discussion: Our findings correspond well with the vaccination schedules, as the highest seropositivity rate was found in children between 0 and 7 years of age. For those older than 7, there was a decline in seropositivity rate despite good vaccine coverage and reached its lowest in the 15–19-year age group. This suggested that certain population groups might be incompletely vaccinated, or the humoral immunity provided by vaccination gradually declined over time.

Conclusions: We recommend a booster dose of MMR vaccine for Thai adolescents in order to prevent future mumps outbreaks.