At what age is it safe to administer Varicella and MMR vaccines?

The administration of the Varicella (chickenpox) and MMR (measles, mumps, and rubella) vaccines is recommended to begin after 12 months of age. This is because the immune system of infants under 12 months is not sufficiently mature to respond effectively to these live attenuated vaccines.

Both the Varicella and MMR vaccines are designed to induce a strong immune response, which is why they are not typically administered before the age of 12 months. The timing allows for the vaccines to provide the best possible immunity and protection against these diseases once the child's immune system is capable of mounting an effective response. It’s also important to note that maternal antibodies can interfere with the efficacy of live vaccines if given too early. Therefore, beginning vaccination after the first birthday ensures that the child has a better chance of developing immunity against these infectious diseases.