Why MMR vaccine is given to 2 years below only?

The MMR vaccine, which protects against measles, mumps, and rubella, is typically administered to children at around 12 to 15 months of age, with a second dose given between 4 to 6 years. This schedule is designed to ensure that children receive the vaccine before they are likely to be exposed to these diseases, especially measles, which can be highly contagious. Vaccinating before age two helps build immunity early in life, as infants are particularly vulnerable to severe complications from these infections. The timing also aligns with the immune system's development, optimizing the vaccine's effectiveness.