Seroconversion of a trivalent measles, mumps, and rubella vaccine in children aged 9 and 15 months

Area of Science:

• Pediatrics
• Immunology
• Vaccinology

Background:

• Maternal antibodies to measles, mumps, and rubella wane by 9 months of age.
• Understanding serological responses to the MMR vaccine in infants is crucial for optimizing vaccination schedules.

Purpose of the Study:

• To evaluate the serological response to the combined measles, mumps, and rubella (MMR) vaccine in 9-month-old infants.
• To compare the response in 9-month-olds to that of 15-month-old children previously vaccinated with monocomponent measles vaccine.
• To assess the safety and efficacy of the MMR vaccine administered at 9 months of age.

Main Methods:

• Serological evaluation of 109 9-month-old infants and 98 15-month-old children.
• Administration of a combined MMR vaccine containing Schwarz, Urabe Am9, and Wistar RA 27/3 live attenuated virus strains.
• Measurement of pre- and post-immunisation antibody levels for measles, mumps, and rubella.

Main Results:

• Pre-immunisation antibody levels were low in 9-month-olds, indicating minimal persistence of maternal antibodies.
• Post-immunisation rubella antibody titres were significantly higher in the 15-month-old group compared to the 9-month-old group.
• High seroconversion rates for all three components were observed in both age groups, with no serious adverse events.

Conclusions:

• The MMR vaccine can be safely administered to infants at 9 months of age.
• The findings support the efficacy of a two-dose MMR vaccination schedule (at 9 and 15 months) for achieving adequate immunity.
• Early infant vaccination with MMR is a viable strategy, with potential for enhanced rubella antibody responses in older infants.