Reassessing the Measles and Rubella Vaccination Schedule

Abstract

BACKGROUND: Because of increased vaccination coverage, more infants are losing maternal protection to measles at earlier ages, but the recommended first dose to protect them is being administered many months after this loss of protection. This gap increases the number of infants susceptible to measles infection and complications. Infants’ serological data, gestational age and maternal vaccination status information were analyzed to determine the efficacy of an earlier two-dose schedule. DESIGN: 120 infants were vaccinated during a measles epidemic in the Netherlands. 46 of the infants were first vaccinated between 6-8 months. 33 of them were first vaccinated at 9-12 months. The infants that were first vaccinated at 6-12 months later received the standard 14-month dose. The remaining 41 were in the control group and were only vaccinated at 14 months, the Netherlands’ standard first dose recommendation. All infants’ measles and rubella antibody titers were measured right before receiving their standard 14-month dose, approximately one month after that standard dose and one year after that stard dose. RESULTS: Infants in control group were unprotected by 14 months. There was no difference in measles or rubella titers at 14 months between groups separated by maternal vaccination status or gestational age. One year after the standard dose, the infants that were first vaccinated at 9-12 months and those in the control group were statistically indistinguishable by both their measles and rubella titers. In addition, both of these groups had statistically higher measles and rubella antibody titers than the infants first vaccinated at 6-8 months. DISCUSSION: Administering the first dose of MMR at 9-12 months and following with another dose during infancy would be effective in establishing immunity and reducing the number of susceptible infants in countries similar to the Netherlands. When necessary, vaccination schedules could be amended to allow for vaccination of infants 6-8 months old as well because after their second dose of vaccine, they are able to establish protective immunity to measles. More research must be done to examine whether a similar a schedule would be effective for lower income countries that face nutritional deficiencies and coinfections. KEYWORDS: measles, rubella, maternal antibodies, interference, MMR vaccine, Netherland, age