An 18-month-old has received an MMR immunization 2 days before the first birthday. Which action is appropriate?

An 18-month-old has received an MMR immunization 2 days before the first birthday. Which action is appropriate?

• A. Administer a reduced dose of MMR now.
• B. Obtain mumps, measles, and rubella titers to determine immunity.
• C. Recommend the next dose of MMR vaccine at 4 to 5 years of age.
• D. Repeat the MMR vaccine since the first dose was given too soon.

Answer: (C)

The main idea here is how MMR dosing timing works when a dose is given too early. MMR is a two-dose series, with the first dose typically given at 12 to 15 months and the second dose at about 4 to 6 years. If a dose is given before the child is 12 months, that early dose doesn’t count toward completing the two-dose series. The catch-up plan is to ensure two valid doses are given in the standard schedule later: one at 12–15 months (as the first valid dose) and the second at 4–6 years. In this scenario, the child is 18 months old and has already received an MMR dose just before turning 1 year, which does not count. The appropriate plan is to ensure completion of the series with the next dose in the standard window later, i.e., at around 4 to 5 years of age. This aligns with completing the two-dose schedule after an invalid early dose, avoiding unnecessary dosing now and focusing on the recommended catch-up timing for the second dose.

The main idea here is how MMR dosing timing works when a dose is given too early. MMR is a two-dose series, with the first dose typically given at 12 to 15 months and the second dose at about 4 to 6 years. If a dose is given before the child is 12 months, that early dose doesn’t count toward completing the two-dose series. The catch-up plan is to ensure two valid doses are given in the standard schedule later: one at 12–15 months (as the first valid dose) and the second at 4–6 years.

In this scenario, the child is 18 months old and has already received an MMR dose just before turning 1 year, which does not count. The appropriate plan is to ensure completion of the series with the next dose in the standard window later, i.e., at around 4 to 5 years of age. This aligns with completing the two-dose schedule after an invalid early dose, avoiding unnecessary dosing now and focusing on the recommended catch-up timing for the second dose.