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

Measles is so contagious that 9 in 10 unprotected people who come into contact with it can become ill, and with cases rising and vaccination rates falling, risks are increasing in some communities.

The CDC issued a warning last week that the measles vaccination rate among U.S. kindergartners has fallen below the herd immunity rate of about 95%. Meanwhile, the number of cases is increasing. In the first 3 months of 2024, the nation surpassed the total number of cases recorded in all of 2023.

What is the trajectory of measles in 2024?

The new CDC estimate predicts there will be about 300 cases of measles in the U.S. this year, which is a far cry from the chart-topping year of 2019, when there were 1,274 cases. But 300 cases would still place the year 2024 in fourth place in terms of the highest number of cases in the last 25 years.

In 2000, measles was declared “eliminated” in the United States, meaning it was no longer consistently present in the country. The measles vaccine became available in 1971, and it took nearly three decades for the country to achieve herd immunity, which usually occurs once about 95% of the population is vaccinated. Since 2000, measles outbreaks have resulted from unvaccinated international travelers bringing measles to the U.S. after being infected abroad and then spreading the disease to other unvaccinated people.

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

“This really may be the only infection that is that contagious, so you really have to get vaccinated to prevent transmission,” explained Catharine Paules, MD, a doctor in adult infectious diseases 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 – Backwards” examines that record year and remembers that the global impact of measles before the development of the vaccine had been in the millions. The disease was so common that there is much data on its toll on the human body, including the risk of 1 in 1,000 cases resulting in possibly fatal neurological complications.

That was the case in one of the largest modern outbreaks in the US, which spanned 2018 and 2019 and occurred in and around Rockland County, New York. An Orthodox Jewish community was at the center of the outbreak caused by international travel. Ultimately, the county counted more than 300 measles cases related to the outbreak. In 2019 alone, New York state had 911 of the country’s 1,274 measles cases.

Unvaccinated children he stayed home and didn’t go to school for 21 days if they were exposed to measles. Public health officials worked to track cases and ask people who were exposed to isolate themselves. There was what one health department official called “an all-out campaign” to vaccinate people against measles, visiting local doctors’ offices, public and private workplaces, and distributing informational signs on neighborhood doors.

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

He noted that following the measles outbreaks of 2018 to 2019, New York state eliminated its religious exemption from school vaccinations.

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

Half of children who contract measles are usually hospitalized. There is no treatment, only supportive care.

Herd immunity not only protects vulnerable children, such as babies who are too young to be vaccinated, but also people with weak immune systems.

“I primarily care for bone marrow transplant patients 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 received transplants are asked to make sure their vaccinations are up to date.

“We run into situations all the time where people are not up to date on their vaccines 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 you can discuss these concerns.

Talking about vaccine doubts

In New York state in 2018 and 2019, the extent of outbreaks was driven by low vaccination rates, although not getting vaccinated is not always the result of vaccine hesitancy or misinformation, Blog noted.

“People got a little complacent and thought, ‘Oh, everyone’s vaccinated and we’re not in danger,’” he said. “It doesn’t take much to reduce vaccination rates and for a disease to become an outbreak. “People don’t believe you when they don’t see it in their community.”