While the vast majority of measles cases in the U.S. and worldwide are occurring in unvaccinated children, a fair percentage is also occurring in adults.  With more-widespread transmission of measles, it’s becoming more important for all of us – yes, that includes parents – to make sure we’re well-protected.

Measles is probably the single most contagious infection that humans face. The key to preventing the return of widespread measles is in keeping vaccination rates high, so even if there is a case, it cannot spread or cause an outbreak. Once there’s a neighborhood, school, or community with a concentration of unvaccinated individuals, it’s only a matter of time before measles returns and spreads widely.

Though we’re used to our children getting vaccinated on well-established schedules that ensure vaccines are safe and effective, many adults have fallen through the cracks.

People born before 1957 are presumed to be immune, because measles was so widespread in the past that almost all children contracted the infection.

Adults considered at “high risk” include healthcare workers, international travelers, those who are living in communities with outbreaks, and university students (I would also include all adults who teach and work in universities, though that’s not part of the official CDC high-risk group). If you’re in these groups, you should have had TWO doses of MMR to ensure immunity. If you’ve only had one, get another; if you’re not sure if you’ve had any, get two doses. The second dose should be four weeks or more after the first.

Other adults (those born after 1957 and who do not live in a community with measles transmission) are considered immune and protected if they’ve had one dose of MMR.

For people born between 1957 and 1968, there’s a catch. Some of the measles vaccine used then was an inactivated vaccine that didn’t confer good immunity. If you have documentation that your vaccine was the “live” vaccine, that’s the good one. If you’re not sure which you received, get one dose of the current MMR to make sure you’re protected.

An alternative to receiving the vaccine, if you’re unsure of your vaccine status, is a blood test for measles titers (IgG antibodies.) If your titers are high, you’re protected; if they’re low, you need another dose of MMR.

The MMR vaccine shouldn’t be given to people with compromised immune systems or pregnant women, though it is fine for nursing moms.

Bottom line: If you’re an adult and you’re not sure if you’re adequately protected, you should receive at least one dose of MMR.

Roy Benaroch is a pediatrician who blogs at the Pediatric Insider. He is also the author of A Guide to Getting the Best Health Care for Your Child and the creator of The Great Courses’ Medical School for Everyone: Grand Rounds Cases.

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