Purpose

This is an immunogenicity study evaluating the development of the immune response of healthy infants following primary vaccination with Attenuvax at 6 or 9 months of age compared with responses in 12 month-old infants receiving MMR-II. Responses of infants receiving an early two dose measles vaccine regimen with the first dose given at 6 or 9 months followed by a second dose administered at 12 months will also be compared to infants given a single dose at 12 months of age (Table 2). The current approved regimen for measles vaccination is a first vaccination at 12-15 months and a subsequent vaccination at school entry. A secondary endpoint of this study will be to assess the safety of measles vaccine administered as Attenuvax at 6 or 9 months of age and in an early two dose measles vaccine regimen with Attenuvax administered at 6 or 9 months followed by MMR-II at 12 months of age.