U.S. Measles Cases Surge, Putting Elimination Status at Risk as PAHO Weighs April Review

In a children’s hospital in Upstate South Carolina this winter, nurses wheeled a toddler into an isolation room with a bright red rash, high fever and glassy eyes. Many of the staff had never seen a case like it outside old training slides.

It was measles.

By mid-March, federal health officials had logged more than 1,300 measles infections across the United States in 2026 — already exceeding the typical annual total and putting the country on pace to rival or surpass last year’s tally. The surge is the most sustained measles activity since the nation was declared to have eliminated the virus in 2000, and it has set up a pivotal decision next month on whether that status still stands.

The Pan American Health Organization, the World Health Organization’s arm for the Americas, is scheduled to meet in April to determine if ongoing outbreaks stretching from West Texas to South Carolina mean measles has re-established endemic transmission in the U.S. If the panel rules that a single measles virus strain has circulated for more than 12 months, the country could officially lose its measles elimination status for the first time in a generation.

Public health experts say the moment is the predictable result of slipping vaccination coverage, widening pockets of unvaccinated children and a decade of increasingly loud attacks on routine vaccines — amplified since the COVID-19 pandemic.

“This is not a bolt from the blue,” said Jennifer Nuzzo, director of the Pandemic Center at Brown University. “We’ve watched vaccination rates decline, we’ve seen the growth of under-vaccinated communities, and now we are seeing the consequences in the form of the deadliest measles outbreaks we’ve had in decades.”

A yearlong chain of outbreaks

The current crisis traces back to Jan. 20, 2025, when health officials in Gaines County, a rural patch of West Texas near the New Mexico border, confirmed a measles case in a resident who had not been vaccinated. The virus spread quickly in a community where, officials said, many parents claim nonmedical exemptions from school immunization requirements.

Within weeks, dozens were sick. Local hospitals reported nearly 100 patients requiring inpatient care at one point, forcing transfers to larger facilities as isolation beds filled.

From there, investigators say, the virus traveled.

Measles cases linked to travelers from the Texas outbreak were later detected in Utah and Arizona. In the summer and fall, separate chains took hold in South Carolina, where state data show childhood vaccination rates had slipped in several counties. By Jan. 20 of this year, federal assessments counted at least 646 measles cases in South Carolina’s Upstate region alone, centered around Spartanburg and neighboring counties.

In 2025, the U.S. recorded 2,284 confirmed measles infections across 45 states and other jurisdictions, the highest annual total since 1991. At least three patients — two young children and one adult — died, all of them unvaccinated, according to regional surveillance summaries.

This year, as of March 12, the Centers for Disease Control and Prevention had confirmed 1,362 measles cases, including 1,353 in U.S. residents, in 31 states. Fourteen distinct outbreaks were ongoing, and about 94% of all cases were tied to those outbreaks. Federal analysts say the country is on pace to surpass last year’s total by spring if transmission is not slowed.

What “elimination” really means

In everyday language, “eliminated” can sound like “eradicated.” In public health, the terms are very different.

The Americas first achieved regional measles elimination in 2016, and the U.S. has been considered measles-free since 2000. Under WHO and PAHO rules, that status does not mean zero cases. Instead, it means a country has no continuous, or endemic, transmission of a measles virus strain for at least 12 months in the presence of strong surveillance. Sporadic infections, often imported by travelers, are expected.

Re-establishment of endemic transmission — and the loss of elimination status — occurs when one lineage of the virus circulates uninterrupted for more than a year.

The long-running chain that began in West Texas in January 2025 and seeded outbreaks in multiple states is at the heart of the April review. Investigators have been tracking whether genetically related virus strains have persisted beyond that 12‑month threshold.

A PAHO spokesperson said in a recent briefing that losing elimination “carries no formal sanctions” but is a “significant public health signal” that a country has “sustained gaps in vaccination and outbreak control.” The spokesperson emphasized that elimination is recoverable when countries intensify immunization and strengthen surveillance, as Venezuela and Brazil have done after prior setbacks.

Vaccination rates fall below a fragile threshold

Measles is among the most contagious pathogens known. In an unvaccinated population, each sick person can infect as many as 18 others. To keep it at bay, health authorities say roughly 95% of people need to be immune — mostly through two doses of the measles, mumps and rubella vaccine (MMR).

Nationally, the U.S. slipped below that line in recent years.

CDC data show that MMR coverage among kindergarten students dropped from 95.2% in the 2019–2020 school year to 92.5% in 2024–2025. That left an estimated 286,000 kindergartners under-vaccinated or unvaccinated against measles last school year. In some communities at the center of recent outbreaks, local coverage has fallen well below 90%.

“The virus exploits the weakest links,” said Walter Orenstein, a former director of the CDC’s immunization program now at Emory University. “You can have a state average of 94% or 95%, but if certain schools or neighborhoods are down at 80%, that’s where measles will spread.”

All states require proof of measles vaccination or immunity for public school attendance, but most allow exemptions on religious grounds and many recognize “philosophical” or personal-belief exemptions. Those exemptions tend to cluster geographically and socially, creating pockets of vulnerability.

The COVID-19 pandemic compounded the problem. Routine well-child visits were delayed, some families fell behind on shots, and political battles over coronavirus mandates bled into debates over long-established vaccines.

Conflicting messages from Washington

The measles resurgence is unfolding against a fractured national debate over immunization.

President Donald Trump and Health and Human Services Secretary Robert F. Kennedy Jr. have both publicly questioned aspects of the childhood vaccine schedule and raised concerns about side effects, resurrecting disputed claims about links between MMR and autism. Major scientific bodies, including the CDC and the National Academy of Medicine, say extensive research has found no such connection.

In February, Mehmet Oz, the physician who heads the Centers for Medicare & Medicaid Services, took a different tack. Speaking in a televised interview about the surge, he urged Americans to get vaccinated.

“Take the vaccine, please,” Oz said. “We have a solution for our problem. This is one you should get your vaccine for.”

Health-policy analysts say this split message — skepticism from top elected leaders alongside urgent appeals from medical agencies — has made it harder for frontline physicians and local health departments to counter misinformation.

The human and economic toll

Most recent U.S. measles patients have been children and teenagers. CDC data from 2025 show that roughly two-thirds of cases occurred in people 19 and younger. The majority were unvaccinated or had unknown vaccination status.

Young children under 12 months, who are not yet eligible for their first routine MMR dose, and people with weakened immune systems are at particular risk.

“Families with infants or kids on chemotherapy are terrified,” said Sruti Nadimpalli, an infectious-disease physician at Stanford Medicine. “They are relying on the rest of us to be vaccinated so measles doesn’t reach them.”

Measles is often dismissed as a routine childhood illness, but before vaccines became widely available in the 1960s it caused an estimated 48,000 hospitalizations and 400 to 500 deaths in the U.S. each year. Complications can include pneumonia, severe dehydration and encephalitis, a dangerous swelling of the brain that can lead to permanent neurological damage.

Modern outbreaks still come at a steep cost. Health economists estimate that each measles case in the United States now generates, on average, about $43,000 in direct medical expenses and public health response costs, including contact tracing and post-exposure vaccination campaigns. A recent state emergency-preparedness report, drawing on federal data, pegged the total cost of 2025’s measles activity nationwide at roughly $244 million.

The virus also disrupts daily life. When a case is detected in a school, unvaccinated students who lack proof of immunity can be barred from attending for up to 21 days after their last exposure — a measure that can repeat with every new infection. Districts in outbreak areas have reported hundreds of students and staff under quarantine and occasional classroom or school closures.

A preventable crossroads

Despite the current surge, experts stress that measles is still controllable.

Two doses of MMR vaccine are about 97% effective at preventing measles, according to CDC studies, and protection is generally long-lasting. Countries that maintain high coverage and respond quickly to imported cases have kept the virus at bay.

What worries researchers now is the trajectory. A modeling study led by scientists at Stanford University projected that if U.S. vaccination rates stay near their recent averages, measles could once again become endemic within about two decades. Under more pessimistic assumptions — with further drops in coverage — the models forecast tens of millions of cases over 25 years.

“This year’s numbers suggest we are closer to that tipping point than we’d like to be,” Nadimpalli said. “If we don’t reverse these trends, we’re going to see measles become a regular, and preventable, part of childhood again.”

As international experts prepare to rule on the country’s elimination status, public-health officials say the decision, while symbolic, should be read as a warning — not a verdict on what happens next.

The virus that once filled American pediatric wards is testing the defenses built over six decades of vaccination. Whether measles again becomes a routine risk in the United States, they say, will depend less on what an international panel decides in April than on choices now being made in statehouses, school boards and pediatric clinics across the country.