What is the recommended course of action for an adult who has not received the Measles, Mumps, and Rubella (MMR) vaccination?

MMR Vaccination for Unvaccinated Adults

Adults born in 1957 or later who have not received MMR vaccination should receive at least one dose of MMR vaccine, with a second dose administered at least 28 days later if they are healthcare workers, students in postsecondary institutions, international travelers, or in outbreak settings. 1, 2

Birth Year Determines Baseline Recommendation

• Adults born before 1957 are generally considered immune to measles and mumps and do not require routine vaccination 3
• Adults born in 1957 or later should receive at least one dose of MMR vaccine unless they have documentation of vaccination, laboratory evidence of immunity, or laboratory-confirmed disease 3, 2

Critical Exception for Healthcare Workers

• Healthcare personnel born before 1957 should NOT be assumed immune and healthcare facilities should consider routinely vaccinating them with 2 doses of MMR vaccine for measles and mumps protection, or 1 dose for rubella protection 1
• This represents a major pitfall—the birth year exemption does not apply to healthcare workers 1

Who Needs Two Doses

A second dose of MMR vaccine (minimum 28 days after the first dose) is specifically recommended for adults who: 3, 1

• Work in healthcare facilities
• Are students in postsecondary educational institutions
• Plan to travel internationally
• Have been recently exposed to measles or are in outbreak settings
• Received killed measles vaccine or measles vaccine of unknown type between 1963-1967
• Were vaccinated with mumps vaccine before 1979 and are at high risk for mumps infection

Dosing Interval and Administration

• The minimum interval between first and second MMR doses is 28 days (4 weeks) for adults aged ≥13 years 1
• If the second dose is inadvertently administered before 28 days, it does not count as valid and must be repeated after the appropriate interval 1
• The second dose is not a booster but addresses primary vaccine failure in the small proportion who don't respond to the first dose 1

Special Considerations for Women of Childbearing Age

• All women of childbearing age should be considered susceptible to rubella unless they have received at least one dose of MMR or have serologic evidence of immunity 2
• Women who lack evidence of rubella immunity and are not pregnant should be vaccinated 3
• Pregnant women should receive MMR vaccine upon completion or termination of pregnancy and before discharge from the healthcare facility 3
• Women must avoid pregnancy for 4 weeks after MMR vaccination 2

Evidence of Immunity (What Counts)

Acceptable evidence includes: 4

• Documentation of age-appropriate vaccination with at least one dose of measles-, rubella-, and mumps-containing vaccine
• Laboratory evidence of immunity
• Laboratory confirmation of disease

Important Caveat

• Provider-diagnosed disease is NOT acceptable evidence of immunity for rubella (though it is acceptable for measles and mumps) 3, 1

Contraindications

Absolute contraindications include: 2

• Pregnancy or planning pregnancy within 4 weeks
• Severe immunodeficiency

Safety Profile

• Serious adverse events are rare, with incidence ≤6 per 100,000 doses 5
• Common non-serious events include arthropathy (263.0 per 100,000 doses), injection site reactions (157.0 per 100,000 doses), and rash (112.9 per 100,000 doses) 5
• Seroconversion rates are 95-100% for each component, with immunity appearing to be long-lasting 6
• Recent studies demonstrate robust immune responses with SRRs of 98.8% for measles, 98.4% for mumps, and 99.5% for rubella after a second dose 7