Early disappearance of maternal anti-measles, mumps, rubella, and varicella antibodies in Indian infants.

BACKGROUND: Immunization of children with vaccines against Measles, Mumps, Rubella, and Varicella (MMRV) is practiced globally with varied recommendations. In India, measles vaccine is administered alone or as MMR at 9 months age. Varicella vaccine is not routinely used. Immunization age is a function of disappearance of maternal antibodies and natural exposure of the children to the pathogens. In view of the measles-WHO-initiative, we aimed to assess if the current immunization age for measles is still valid. In addition, the kinetics of IgG and IgM antibodies against rubella, mumps and varicella viruses was also examined.

METHODS: This cross-sectional study was conducted at a tertiary care hospital in Pune, India. A total of 600 children, 150 each in 6-month/9-month (no vaccination) and 12-month/15-month (minimum 4 weeks post-measles-vaccine) cohorts were included. History of these infections and birth status (term/preterm) was recorded. All serum samples were screened for IgG-anti-MMRV-antibodies while IgG-positives were tested for specific IgM antibodies (ELISA).

RESULTS: At 6-months, the prevalence of MMRV antibodies was 4.7%, 2.7%, 10.7%, 5.3% respectively depicting disappearance of maternal antibodies in majority of the children. Birth status did not influence antibody positivity. Despite vaccination at ∼9-months, >25% children were still susceptible to measles virus at the age of 12/15-months. The ratio of clinical:subclinical infections was 4:10 (measles) and 12:1 (varicella). All the mumps/rubella IgM positives (1 and 2 respectively) represented subclinical infections.

CONCLUSION: Demonstration of early disappearance of maternal antibodies against MMRV viruses leading to the risk of these infections at an early age emphasize need for early immunization of Indian children. Suboptimal response to measles vaccine needs to be seriously addressed especially in view of the WHO's initiative for measles eradication.