What is the maximum interval recommended between doses of the MMR vaccine for adequate immunity?

The maximum interval recommended between doses of the MMR (measles, mumps, rubella) vaccine for adequate immunity is 28 days. This timeframe allows the immune system enough time to respond to the first dose and build an adequate immune response that can be further boosted by the second dose.

The MMR vaccine is typically administered as a two-dose series; the first dose is given between 12 and 15 months of age, and the second dose is usually given between 4 and 6 years of age. The 28-day interval ensures that the second dose does not interfere with the immune response generated by the first dose. While administration can occur sooner than 28 days in certain circumstances, spacing doses apart by at least this recommended interval is crucial to achieving optimal immunity against the diseases covered by the vaccine.

This rationale underpins standard immunization practice, balancing efficacy with the body's capacity to mount a supportive immune response to vaccinations.