Measles in the US: 5 Things You Need to Know

David Sugerman, MD, MPH


December 13, 2022

Editorial Collaboration

Medscape &

1. Measles is circulating, and undervaccinated communities are at risk.

While overall childhood vaccination rates remain high in the United States, measles cases still occur here. Measles is easily imported by unvaccinated travelers and can spread in underimmunized communities and even cause outbreaks.

Because there are unvaccinated and undervaccinated "pockets" in communities around the country, it's vital to understand your patient population. Even if pediatric patients or their families have not traveled recently, they may still be at risk within a community where its members travel internationally. If you see patients who come from measles-endemic countries such as Afghanistan, Somalia, Pakistan, or Kenya, assess their vaccination history and offer all recommended vaccines, including MMR for measles, mumps, and rubella, and IPV for polio.

Low community-wide vaccination coverage may be partly due to persistent anti-vaccine myths within insulated subcommunities, especially ones with low MMR coverage and frequent travel back to their home countries with ongoing measles outbreaks. Your strong recommendation for vaccination can help boost vaccine confidence, making both individuals and the community as a whole safer. There are resources to help you with these discussions.

Unfortunately, the unfounded concerns specific to MMR vaccine and autism remain, placing unvaccinated children at risk for measles. Because signs of autism may appear around the same time children receive the MMR vaccine, some parents may worry that the vaccine causes autism. Vaccine safety experts, including experts at the American Academy of Pediatrics (AAP) and CDC, agree that MMR vaccine is not responsible for increases in the number of children with autism.

Your patience is needed to reaffirm the importance of protection against measles. You may need to explain the severity of measles and help patients understand the risk to themselves, their children, and their community; this can go a long way toward vaccine acceptance.

2. Know when to consider a measles diagnosis, and what to do.

Healthcare providers should consider measles in patients presenting with febrile rash illness and clinically compatible measles symptoms, especially if the person recently traveled internationally, was exposed to a person with febrile rash illness, or if known measles cases are circulating in your community. Prodromal measles symptoms may also include fever, cough, coryza (ie, runny nose), or conjunctivitis.

From first contact with any suspect patient, obtain both a serum sample and a throat swab (or nasopharyngeal swab). Urine samples may also contain virus, and when feasible to do so, collecting both respiratory and urine samples can increase the likelihood of detecting measles virus. Don't forget, healthcare providers are required to report any suspected measles cases to their local health department.

3. MMR vaccine is highly effective — are all your patients up-to-date?

One dose of MMR vaccine is approximately 93% effective at preventing measles; two doses are approximately 97% effective. Almost everyone who does not respond to the measles component of the first dose of MMR vaccine at age 12 months or older will respond to the second dose. Therefore, the second dose of MMR is administered to address primary vaccine failure.[1] You can keep up to date on all Advisory Committee on Immunization Practices (ACIP)za recommendations and find patient resources as well on the CDC vaccines website.

4. Consider postexposure prophylaxis after known exposure.

People exposed to measles who cannot readily show that they have evidence of immunity against measles should be offered postexposure prophylaxis (PEP). Therefore, to potentially provide protection or modify the clinical course of disease among susceptible persons, either administer MMR vaccine within 72 hours of initial measles exposure, or immunoglobulin (IG) within 6 days of exposure. Do not administer MMR vaccine and IG simultaneously, as this practice invalidates the effectiveness of the vaccine.

5. Known cases need isolation — make sure your staff are adequately informed and protected.

Infected people should be isolated for 4 days after they develop a rash; airborne precautions should be followed in healthcare settings. Because of the possibility, albeit low, of MMR vaccine failure in healthcare providers exposed to infected patients, they should all observe airborne precautions in caring for patients with measles. Further infection control guidelines may be found here: Interim Measles Infection Prevention Recommendations in Healthcare Settings | CDC.