Could U.S. Measles Cases Break a Record This Year? What to Know

April 12, 2024 – When a mother in Atlanta, GA, noticed measles symptoms in her son earlier this year after returning from an international trip, she knew just bringing him straight into a local emergency room may put others at risk.

She kept him in the car outside the ER while alerting staff inside.

“We were able to immediately bring the child in and immediately put him in an isolated room and mask and avoid potential exposures, but it could have gone very differently,” said pediatric infectious disease specialist Matt Linam, MD, whose colleagues at Children’s Healthcare of Atlanta treated the patient.

The boy, who was older than 5 years of age and unvaccinated, recovered from measles after being hospitalized.

Federal health officials are urging medical and public health organizations to be on the lookout for potential measles cases as outbreaks of the disease are mounting rapidly this year. 

“A lot of the symptoms of measles — fever, cough, red eyes, a rash, although it may not have developed yet — there are a lot of other things that can present that way,” Linam said. “If you’re not able to identify it very quickly and get that child and their family isolated very quickly, you can have a lot of health care exposures.”

The scenario of the mother in Atlanta giving health care workers a heads up is unusual. Numerous communities have received alerts in recent weeks that people may have unknowingly been exposed to measles in everyday places like a Walmart in suburban Chicago or a medical center in California. 

Measles is so contagious that 9 out of 10 unprotected people who come in contact with it may get sick, and with cases on the rise and vaccination rates dropping, risks are spiraling in some communities. 

The CDC issued a warning last week that the vaccination rate for measles among U.S. kindergarteners has fallen below the herd immunity rate of about 95%. Meanwhile, case counts are climbing. Within the first 3 months of 2024, the nation surpassed the total number of cases recorded in all of 2023.

The most recent CDC tally of nationwide measles cases stands at 113 in 2024, nearly doubling in less than 2 weeks. The pace is so quick that CDC data scientists published a projection to examine whether measles is on track for a record-breaking year.

What’s the Trajectory for Measles in 2024? 

The CDC’s new estimate predicts there will be about 300 cases of measles in the U.S. this year, which is far off from the chart-topping year of 2019, when there were 1,274 cases. But 300 cases would still rank the year 2024 as fourth for most cases in the past 25 years.

In 2000, measles was declared “eliminated” in the U.S., meaning it was no longer constantly present in the country. The vaccine for measles became available in 1971, and it took the nation nearly 3 decades to achieve herd immunity, which typically occurs once about 95% of a population is vaccinated. Since 2000, measles outbreaks have been a result of unvaccinated international travelers bringing measles back to the U.S. after being infected abroad, then spreading the disease among other unvaccinated people. 

But vaccination rates have slipped so far that now, there is a strong possibility that the disease will lose its “eliminated” status and once again begin to regularly circulate and spread in the U.S., according to a new CDC report published Thursday.

“This really may be the only infection that’s this contagious, so you really have to vaccinate to prevent transmission,” explained Catharine Paules, MD, an adult infectious diseases doctor  at Penn State Health Milton S. Hershey Medical Center in Hershey, PA.

Paules, along with Anthony Fauci, MD, and others published a paper in the New England Journal of Medicine titled “Measles in 2019 – Going Backward” examining that record-setting year and recalling that the global impact of measles prior to vaccine development had been in the millions. The disease was so common that there is plenty of data about its toll on the human body, which includes the risk of 1 in 1,000 cases resulting in possibly fatal neurological complications.

Lessons Learned From Measles in 2019 

Today, health officials examine measles on an outbreak basis, which is almost entirely dependent on whether people in a community have been vaccinated. 

“It’s really different than other infections that are less transmissible,” Paules said. “We were able to prevent the spread of COVID by doing things like social distancing and masking. But measles is so contagious that you really have to rely on vaccines to get outbreaks under control.”

That was the case in one of the largest modern outbreaks in the U.S., which spanned 2018 and 2019 and occurred in and around Rockland County, NY. An Orthodox Jewish community was at the center of the outbreak that was sparked by international travel. The county ultimately tallied more than 300 measles cases linked to the outbreak. In 2019 alone, New York state had 911 of the nation’s 1,274 measles cases.

Unvaccinated children stayed home from school for 21 days if they were exposed to measles. Public health officials worked to trace cases and ask people who were exposed to isolate. There was what one health department official called “an all-out” campaign to get people vaccinated against measles, visiting local doctor’s offices, private and public workplaces, and distributing door hangers with information in neighborhoods. 

“There was a huge increase in the number of vaccines given, and I think that’s ultimately what stopped the outbreak,” said Debra Blog, MD, MPH, medical director for the New York State Department of Health’s vaccine division, whose 25-year career spans working as a pediatrician and public health official in New York as well as time at the CDC.

She noted that following the 2018 to 2019 measles outbreaks, New York state removed its school immunization religious exemption.

Children typically receive their first dose of measles vaccine around age 1, and the second dose dose is recommended between the ages of 4 and 6, according to the American Academy of Pediatrics. But children can receive the second dose as soon as 28 days after the first dose, which boosts protection from 93% to 97%.

Last week, the CDC said the vaccination rate for measles among U.S. kindergarteners has slipped from 95% to 93%, and much lower in some communities. During the 2020 to 2021 school year, there were a quarter million kindergarteners attending school who weren’t vaccinated against measles.

CDC data scientists estimate the current vaccination rate of 93% means a single child with measles attending a school of 100 kids would lead to about 10 people likely getting sick. As the vaccination rate declines in the school, the number of people likely to get sick rises at an increasing rate, reaching nearly one-third of the school potentially becoming ill if the vaccination rate drops to 70%.

Half of children who get measles typically are hospitalized. There is no treatment, just supportive care.

Herd immunity not only protects vulnerable children such as infants who are too young to be vaccinated, but also people who have poor immune systems.

“I see bone marrow transplant patients primarily and help treat infections in that population,” Paules said. “We can’t give them some of these vaccines, including the measles vaccine because it’s a live vaccine.”

Close friends and family members of people who have had transplants are asked to ensure they are up-to-date on vaccines.

“We run into situations all the time with people not being up-to-date on vaccinations for a variety of reasons, and we find that people want to protect their loved ones,” said Paules, who suggests that anyone with concerns about vaccination find a trusted medical professional with whom they can have a conversation about those concerns.

Talking About Vaccine Hesitancy 

In New York state in 2018 and 2019, the scope of the outbreaks was fueled by low vaccination rates, although not getting vaccinated isn’t always a result of vaccine hesitancy or misinformation, Blog noted.

“Folks were kind of complacent and thought, ‘Oh, everybody’s vaccinated and we’re not in danger,’” she said. “It doesn’t take much to lower vaccination rates and have a disease become an outbreak. People don’t believe you when they don’t see it in their community.”

“We are such a mobile society and disease outbreaks are only an airplane flight away,” Blog continued. “We still have to remain vigilant about getting vaccinated and about addressing vaccine hesitancy. Community trust and involvement are key.”

For anyone who has a friend or family member or colleague who is vaccine hesitant and wants to help that person, the first step is to manage your own mindset when entering the conversation, and the second step is to be a patient listener, advises Linam, based on his interactions with the parents of his patients.

“A lot of times, there’s a tendency to demonize these parents and say, ‘You’re hurting your child and you don’t care about them.’ I think that couldn’t be farther from the truth. The important thing in working with family, friends, colleagues, or patients, is to remember first and foremost that these parents are no different than you or I, and they want what’s best for their children and want to keep them safe.”

Remember that they are genuinely feeling uneasy after hearing or reading something about vaccines.

“What I try to do when I’m in those situations is, first, I check myself and remind myself that they want what’s best for their child. Then, I listen to them. I try to understand their specific concerns because often that helps how you respond,” Linam said, suggesting that the American Academy of Pediatrics website might be a resource for them to learn more about their questions.

“It’s usually not a one-and-done sort of conversation,” he said. “You have to be patient.”