It Was Once Eliminated From the U.S. Now, We Could Be on the Verge of an Epidemic. (2025)

Sign up for the Slatest to get the most insightful analysis, criticism, and advice out there, delivered to your inbox daily.

As of this week, there are at least 800 cases of measles in the U.S. across 25 states. There are 10 outbreaks—defined as three or more related cases—ranging from New Mexico to New York. The largest outbreak, with 597 cases, started in Texas back in January. That’s where we had the first death of an unvaccinated child, in February. Another in April. Three in total. Before this year, there had been three deaths in all of the years since the U.S. eliminated the disease (meaning that the disease was no longer continuously spreading) in 2000.

It’s concerning. The numbers are high, especially considering we’re less than halfway through the year. It’s very possible that cases are being underreported. And they keep rising, with no evidence that it will slow anytime soon. Which leads us to the million-dollar question: How bad could measles get this year?

While it’s impossible to say for certain, experts say that we’re standing on a precipice. It’s not out of the question that measles could rip through the entire country like wildfire. If each case is a spark, “the brush is burning right now,” says epidemiologist Michael Mina, who studies how infections and vaccines affect human health. Whether the burning brush will ignite the whole forest just depends on how long our strained firewalls can hold.

Measles could continue breaking out in these bubbles (bad, but relatively confined to certain geographic areas). Or, if those bubbles grow large enough, they could converge and turn into a countrywide epidemic (very, very bad). To imagine how bad it could get, we can look to Europe, Mina recently argued in a New York Times op-ed. In 2018, the continent saw more than 80,000 cases, tens of thousands of hospitalizations, and over 70 deaths, Mina says, including in countries that had achieved—and subsequently lost—elimination status. That’s possible here, too.

If it feels like this is happening suddenly, it’s not. The U.S. has been moving toward this moment for decades, says Mina, long before Robert F. Kennedy Jr. became health secretary. There are a mix of factors. For one, public health is often a victim of its own success: Once a disease has been wiped out for long enough, people forget how bad it was. In the days before the measles vaccine (aka the MMR vaccine), almost every kid got measles, says David Weber, president of the Society for Healthcare Epidemiology of America. Every year 3 million to 4 million people were infected; nearly 50,000 people were hospitalized; hundreds died. The vaccine changed that. Those who survived the disease decades ago might protest, Hey, I had the measles and just stayed home for a week, no biggie! People forget how many people died, says Weber. Not to mention, there are new parents today who never had to deal with the measles at all. For many, the idea of their kid getting the measles feels totally theoretical.

The consequence of improved public health is that it becomes harder to convince people to go out of their way to vaccinate. Vaccination has always been hard to argue for; sticking a child with a needle full of some substance “goes against a parent’s natural evolutionary instincts,” says Mina. He doesn’t fault parents who worry about vaccination. Instead, he says, it’s the onus of public health officials to make sure parents are “exceedingly comfortable” to push back against those (totally reasonable!) instincts and make an informed decision to protect their child. That requires making sure parents have the information they need to evaluate the risks and benefits of a shot.

Vaccine messaging by public health officials has left much to be desired, says Mina. Instead of acknowledging and addressing parents’ worries, they’ve taken a more paternalistic approach—i.e., “Just get the vaccine, it’ll be fine!” Then, early on in the pandemic, the Centers for Disease Control and Prevention assured people that you couldn’t get COVID-19 after getting vaccinated, when you could in fact still get COVID-19, albeit a much milder version. People felt like they’d been lied to, recalls Jess Steier, CEO of the public health data science consulting firm (andpodcast)Unbiased Science. “They burned the bridge of trust.”

Add all that to the fact that the MMR vaccine has been erroneously linked to autism (studies continue to show no association between vaccines and autism). The seed was planted way back in 1998 thanks to a paper in the Lancet—a paper that was later found to be riddled with faulty data and has since been retracted. But that didn’t matter. It had already set off a movement, fanned by RFK Jr. and other vaccine cynics. Indeed, measles vaccination rates had been dropping for many years before the pandemic came along.

And we really need people to get the vaccine. Measles is incredibly contagious, far more so than COVID or flu. A single person with measles can walk through, say, a grocery store and continue to infect people for up to two hours after they’ve left the space, says Weber. Roughly 90 percent of unvaccinated people exposed to measles will become infected.

While measles’ mortality rate is relatively low compared with other diseases—about 0.2 percent of people infected with measles in the U.S. will die—the hospitalization rate is incredibly high: 20 percent, for people who haven’t been vaccinated. “This is not a benign disease,” says Weber. “How many infectious diseases do we have that 10 to 20 percent of the people end up in the hospital?” (It’s certainly not that high for flu, COVID, or other respiratory illnesses.)

All that being said, here’s the very worst-case scenario for what could happen next with measles, according to Steier’s calculations. Given measles’ mortality rate of 0.2 percent, if the entire unvaccinated U.S. population (23.5 million people) were exposed to measles, nearly 50,000 people could die. (This would likely occur over several years.) Given that 90 percent of exposed unvaccinated people become infected, and then 20 percent of that number face hospitalization, millions could end up in the hospital, and some with potentially lifelong complications, including neurological damage, intellectual disabilities, and hearing loss. They also face the risk of something called immune amnesia, where the immune system “forgets” its immunity to other infectious diseases for a period of weeks to years. Even if they survive the measles, they could suffer or die from something else because they got the measles. None of these calculations include the 22 million immunocompromised Americans who face heightened risk even if they were vaccinated.

It’s unclear what a nationwide outbreak would mean for the vaccinated population, says Steier. The MMR vaccine is incredibly effective—roughly 97 percent of people are protected with two shots—but it’s not been tested in an environment where there are thousands of cases. “We could see more breakthrough cases of measles, potentially,” she says.

It might also change how we live our lives. Like COVID days, we could see travel advisories or requirements to carry proof of immunity (which could cause procedural challenges, considering how many people are immune due to prior infection and thus have no vaccination records to prove their immunity, says Weber). This, of course, will depend on how the federal government responds.

Again, those are worst-case scenarios. How exactly measles will play out isn’t certain. But the way forward is clear, experts say: The only thing that can end the spread of measles is the MMR vaccine, full stop. That’s our firewall. In the current outbreaks, 96 percent of people who have been infected are unvaccinated or have an unknown vaccination status. In the case of a measles infection, which can take days to develop symptoms, even a vaccination right before an individual gets exposed and infected can still make a difference in protecting them. That means “catch-up” vaccination campaigns can be “very, very powerful” if an unvaccinated community gets hit hard with measles, says Mina. In other words, there are things that can be done late in the game, even if we cross into wildfire territory.

Alas, we continue to see mixed messaging about vaccines by the Department of Health and Human Services. In the past, kids dying of measles might have led to swift action by the CDC, such as widespread catch-up vaccination campaigns (some CDC employees have been deployed to Texas, though resources are low after federal funding cuts last month). But even after the first child’s death in February, RFK Jr. continued to question the MMR vaccine and tout therapies, like vitamin A, that are not preventive measures. It wasn’t until early April that he finally endorsed the vaccine. And yet “the only way that we can prevent measles is MMR,” says Steier. “It’s bananas that we’re talking about anything else.”

The good news is that, regardless of lagging federal efforts, individuals can opt to protect themselves with a vaccine that is incredibly effective. If you’re in an outbreak area or planning to travel, make sure you and your children are vaccinated, says Weber. Infants can receive an early vaccine at 6 months (this would not be considered to be one of the standard doses, so they’d later still need the full two-shot regimen). As the threat has grown more imminent, “we are seeing an increased awareness amongst millions of people,” notes Mina. Hopefully many of them will update their risk-benefit analysis and get vaccinated, he says.

In the meantime, experts are keeping an eye out for red flags that we’re going the wrong way. If outbreak bubbles continue to grow—or worse, converge—we move closer toward a national epidemic, Mina says. Steier worries about a study that RFK Jr. has ordered to investigate the link between autism and vaccines, which will be headed by David Geier, a man who has been disciplined for practicing medicine without a license, has no advanced science degree, and has suggested for decades that vaccines cause autism. If the study claims to find a link (again, the existence of such a link has already been investigated thoroughly and disproven), Steier anticipates that vaccination rates could plunge—the opposite of what needs to be happening.

Until vaccination rates improve, we’ll teeter on the edge with this disease. It’s not clear what will happen with measles next—but we’re not in a good spot.