Persistence of Antibodies against Measles, Mumps, and Rubella after the Two-Dose MMR Vaccination: A 7-Year Follow-Up Study

Abstract

In 2014, the Expanded Program on Immunization of Thailand changed the timing of the second dose of the measles-mumps-rubella (MMR) vaccine from 4-6 years to 2.5 years, while maintaining the first dose at 9 months of age. This study aimed to examine the dynamics and durability of immune responses induced by the two-dose MMR vaccine in a group of 169 Thai children from 4 to 7 years of age (4.5 years after the second MMR dose). We followed a cohort of healthy children from a clinical trial (ClinicalTrials.gov NCT02408926) where they were administered either the Priorix vaccine (GlaxoSmithKline Biologicals, Rixensart, Belgium) or M-M-RII (Merck & Co., Kenilworth, NJ, USA) at 9 months and 2.5 years of age. Blood samples were collected annually from ages 4 to 7 years. Anti-measles, -mumps, and -rubella IgG levels were evaluated using the enzyme-linked immunosorbent assay (EUROIMMUN, Lubeck, Germany). A total of 169 children completed this study. Over the 4.5 years following the two-dose MMR vaccination, we observed a decline in the seroprotection rates against measles and mumps, but not rubella. Longitudinal monitoring of antibody persistence, among other strategies, will help predict population-level immunity and inform public health interventions to address potential future outbreaks.

Keywords: antibody; children; measles; mumps; persistence; rubella.

Figure 1

The consort flow diagram of this study.

Figure 2

Serologic status and GMCs of antibodies against (A) measles, (B) mumps, and (C) rubella from birth until 7 years of age. The right y-axis represents the percentage of the population with a given antibody concentration; the left y-axis represents the GMC at each age. The syringe icon below the x-axis represents the administration of the MMR vaccine at 9 and 30 months. Data between birth and 36 months were previously published in ref [11].