Will U.S. keep or lose its status as country that ‘eradicated’ measles?

Health officials this week said ongoing measles outbreaks could remove the status of the U.S. as a country that has “eliminated measles.” Despite random cases on a small scale in the intervening years, America has proudly claimed to have done away with the highly contagious disease since the early 2000s.

Canada already lost its status earlier this month, 27 years after gaining it, for failure to control an outbreak that started in October 2024 at a Mennonite event.

A country is stripped of the designation, which is given by the World Health Organization, if an outbreak cannot be controlled within a year. So the anniversary of the outbreak’s beginning last January in Texas will be the deciding point on whether the U.S. is considered “measles-free” if more recent cases are linked to it. A country is measles-free if no outbreak lasts an entire year.

There were 16 small outbreaks in 2024 in the U.S. LiveScience Daily reports there have been 45 U.S. outbreaks this year and that many could lead to endemic spread in the near future. In all, the U.S. has seen 1,723 lab-confirmed individual cases, according to data the Centers for Disease Control and Prevention presented to the Pan American Health Organization earlier this month.

Most of the cases are in people who are unvaccinated or whose vaccination status is unknown, per that presentation.

A significant outbreak is in Arizona and Utah, with more than 180 cases between them. The New York Times earlier reported that the outbreak in the two states had been genetically linked to the Texas outbreak, but on Thursday retracted that a genetic link had been found. Such a finding would have pressured the two states to control their shared outbreak before the January anniversary of the Texas outbreak.

The retraction doesn’t eliminate the risk that the U.S. will no longer be considered measles-free.

“We still don’t know how the determination will come up in January,” Dr. Diego Hijano, an infectious-disease specialist at St. Jude Children Research Hospital, told LiveScience Daily. “But it’s likely, as they look at the cases that started off in Texas and have continued to spread, that they will think there have been 12 months of cases coming from that area.”

About measles

Measles is among the most contagious illnesses. And it can linger in the air for up to two hours after someone with measles comes through, putting people at risk if they simply occupy the same space occupied by someone who was ill.

The viral illness is misunderstood to the extent that people see it as a benign illness that might be temporarily uncomfortable but is no big deal.

In fact, measles can have serious or even fatal complications. The CDC said 1 to 4 of every thousand children will die because of measles, as it can be more than the high fever and rash that dominate its symptoms. One very rare but deadly complication (as many as 11 of every 100,000 measles survivors get it) is subacute sclerosing panencephalitis, which is a degenerative nervous system disease that shows up way down the road, long after folks think they’ve recovered.

There are other complications, as well, including among women who are exposed to measles while pregnant.

Measles in Utah

Utah has had 87 lab-confirmed measles cases this year, per data from the Utah Department of Health and Human Services. Dr. Leisha D. Nolen, state epidemiologist, said most of the cases are in the southern part of the state, but there have been cases — including recently — in the north, as well.

Nolen said that Utah public health officials are working closely with the CDC and public health officials in neighboring states to track who is getting infected and where it is occurring.

“That is what we would expect,” Nolen said. “We know this vaccine is exceptional, but not perfect and the person who did have a breakthrough was very strongly exposed. The people who get infections even if they are vaccinated tend to be the people who are around somebody who is extremely sick or in the same household where they’re getting really strong exposure.”

So far, she said, there’s just one case that is considered a “breakthrough,” because the person got measles in spite of being vaccinated. The other cases either involved people who are not vaccinated or whose vaccination status is not known.

Among other questions, public health officials tracking the disease spread ask those with measles whether they know where they were exposed, if they traveled and whether they were around people who are ill. Lots of people know exactly where they were exposed and others have no idea they were anywhere near a case of measles, she said.

Avoiding measles — and advice for if you can’t

The Measles, Mumps, Rubella (MMR) vaccine is the best way to avoid the measles, Nolen said. Although there can be breakthrough cases, having been vaccinated also reduces the severity of the illness.

“We are encouraging everyone to be vaccinated as much as possible,” she said, noting an increase in uptake of the vaccine right after the first two Utah cases. But she added that has “somewhat dropped off.”

Nationally, skepticism about the measles vaccine has also grown in recent weeks, with an increase in those seeking an exemption to school vaccine requirements.

Because measles is so contagious, those who believe they might be sick with measles need to let their doctor or clinic know before going to seek treatment, Nolen said. Otherwise, there’s a chance that everyone in the waiting room or other areas the infected individual occupied could become ill. Per Nolen, with advanced notice, someone with measles exposure can be ushered in by a different door or other precautions can be taken.

Hygiene is, of course, extremely helpful to avoid measles. Avoid surfaces that might have been touched (including doorknobs and handrails) and if you share a household, be sure to wipe down surfaces with a disinfectant.

But maintaining distance is especially important.