Parents have been calling pediatricians across the city with questions about the measles following an outbreak in Texas and reports of a case of measles in a King County infant last week. We checked in with Dr. Mary Fairchok at Mary Bridge Children’s Hospital in Tacoma to discuss common misconceptions about measles.
Fairchok is board certified in pediatrics and pediatric infectious disease, has authored more than 40 peer-reviewed medical articles, and has presented lectures on infectious disease research both nationally and internationally.
If measles is a “childhood disease,” why is it still contagious for adults?
Dr. Fairchok: Whether or not an individual is susceptible to measles has to do with their immune status, not how old they are.
By 2000, we had eliminated measles out in the U.S. — we had such good levels of herd immunity in the community from vaccinations by 2000 that an unvaccinated child or adult could travel overseas, get infected, and come back to the U.S, but not start an outbreak. However, due to vaccine misinformation, we have now dropped below herd immunity levels in some areas of the country.
The CDC says 95 percent of people must be vaccinated to protect against measles outbreaks. Currently, 90.7 percent of King County kindergartners are vaccinated. In Gaines County, Texas, the center of the current measles outbreak, only 82 percent of residents are vaccinated against the disease. Texas allows parents to file for a non medical exemption (philosophical or religious) to vaccination for their children, and one of the school districts in this county, the Loop Independent School District, had a 47.95 percent non-medical exemption rate in 2023-2024, the highest known percentage of exemptions of any public school in Texas. Time and again, outbreaks in the US of measles have coincided with communities that have low immunization rates, allowing an outbreak to occur.
Dr. Mary Fairchok is a MultiCare Mary Bridge Children’s pediatrician. (Image courtesy Mary Bridge)
Is measles contagious for anyone who is NOT immune?
Dr. Fairchok: Yes. Anyone who is not immune is susceptible to measles infection. Also, of note is that a person with a significant immunodeficiency may not be immune regardless of whether they have been infected before or were immunized.
The following types of people ARE immune, if they are not severely immunocompromised:
- Anyone who actually had confirmed measles infection before. Most people born before 1957 are presumed to be immune as the vast majority would have had measles.
- Anyone who had a blood test that showed a positive titer to measles. This is the antibody that is produced when you are immune, whether from the disease or from immunization.
- 97 percent of people who are fully immunized with the current vaccine (eg received 2 doses); 3 percent are non-responders to the vaccine.
- Some people who received just one dose of the current vaccine. This group would include people who were only immunized between 1968-1989. We went to two doses in 1990 to get up to 97 percent coverage. One dose only works for about 93 percent of people. So it is recommended to check with your doctor to see if you need a second dose.
- People who only received the original vaccine between 1963-1967. This group is less likely to be immune because that vaccine did not work as well. It is recommended that these people get a dose of the current vaccine (MMR).
Of note is that the vaccine is a live attenuated vaccine, meaning that it is made from a live measles virus that has been altered to not cause infection. As such, it should not be given to pregnant women or people with significant immunocompromise. It also isn’t given under six months because that age usually already has protective antibody from their mom, and between 6-12 months unless there is an outbreak.
Could you clear up common misconceptions you’ve heard from patients about measles?
Dr. Fairchok: The vaccine does not cause outbreaks. In rare cases, this vaccine can cause a mild rash and cold symptoms in the vaccinated person about 2-3 weeks after receiving the vaccine. It can cause vaccine-related measles in someone severely immunocompromised. However, it does NOT spread from person to person like the wild type measles. There has never been a case of transmission of the vaccine measles virus to another person.
Measles is not just a mild childhood illness. Although only approximately 1-3 in 1,000 will die of measles, many complications can occur. About 20 percent will need to be hospitalized due to pneumonia or other complications. Children under age five are particularly at risk for more severe infections. Measles can cause blindness, deafness and brain damage. Rarely, a fatal brain condition can occur 7-10 years after infection. Finally, measles affects the immune system’s ability to fight off other infections for about two years — measles can cause loss of immune memory to other infections.
Vitamin A neither prevents nor cures measles. Measles can be more severe in patients who are vitamin A deficient, so vitamin A should be administered under a doctor’s supervision in cases where vitamin A deficiency exists. Vitamin A deficiency is rare in the US. For severe measles, such as hospitalized cases, we also administer Vitamin A because measles can cause Vitamin A levels to go down in the system. Administration of Vitamin A in these situations can decrease the severity of measles. However, it does not prevent measles, and it does not make the symptoms of measles go away any faster or prevent the immune system damage or long term complications. Too much vitamin A is toxic and also dangerous to fetuses.
Is the current Texas outbreak related to record-low vaccination rates?
Dr. Fairchok: Yes. The current outbreak spread in a community because that area of Texas had very low levels of immunization as described above.
How can folks know they’ve been exposed?
Dr. Fairchok: You won’t know you’re exposed unless you are told that you were exposed or someone you were in close contact with during their contagious period was diagnosed with measles. People with measles are contagious from four days before the rash appears to four days after the rash appears. Check the Public Health: Seattle and King County website for potential exposures. Measles is one of the most highly contagious viruses around. One person can infect an average of 15 other non-immune people.
How can the vaccine retroactively protect those exposed in the last 72 hours?
Dr. Fairchok: The incubation for measles after exposure is 7-21 days. So if you give the vaccine within 72 hours of exposure, your body has time to respond to the vaccine before the virus has reproduced enough to cause disease.
What should those who can’t get the vaccine do?
Dr. Fairchok: Infants under six months of age or immunocompromised or pregnant people can get passive protection with a shot of IMIG or an infusion of IVIG within six days of exposure. The best strategy is to get vaccinated if you are eligible.
What else should the community know?
Dr. Fairchok: Do not get your information from social media, viral memes, or podcasts, etc. There is a lot of misinformation being circulated. Get your information from your trusted pediatrician or family physician.
What should parents or children do if they think they’ve been exposed?
Dr. Fairchok: If they are not severely immunocompromised (eg AIDS patient, or patient on chemotherapy, bone marrow transplant patient, etc) and have immunity (eg either a history of having had the measles, or two doses of MMR, or had an antibody test at some point confirming immunity) they don’t need to do anything other than monitor for symptoms, which would be unlikely to occur. DOH also does contact tracing of known cases, so for a confirmed exposure, you are likely to get a call with instructions.
If you are severely immunocompromised, unvaccinated or inadequately vaccinated, or aren’t sure if you are adequately vaccinated, then call your provider or local health jurisdiction to discuss. You should also stay home starting at seven days after exposure through 21 days in quarantine if you are confirmed to have been exposed and are not immune. It is important to call as soon as possible because you/your child could be immunized within 72 hours or given immunoglobulin within six days to reduce the likelihood of infection.
The early symptoms of measles are basically the same as a bad cold/cough and start on an average of 11-12 days after exposure, while the rash begins about two days later (average of 14 days after exposure). However, the incubation between exposure and when symptoms show up ranges from 7-21 days. You are also contagious from four days before onset of rash to four days after onset of rash. It’s very important not to just go to an emergency department or clinic if you think you have measles unless it is a true emergency because you can expose others — better to call first. If you do go to a medical facility, call first and put on a mask and let them know immediately that you think you might have measles.
