The holidays are approaching and case counts are surging, but quarantine orders are in full effect, and public health officials warn the spread of disease is ongoing. That’s how many Americans experienced December 2020 during the COVID pandemic, and it’s also how hundreds of people under quarantine—including more than 100 elementary school students—in Spartanburg County, South Carolina, have spent recent weeks as a measles outbreak has continued to grow.
The county is the latest measles hotspot in a year that saw a large outbreak in West Texas—762 cases that included the deaths of two children—and ongoing outbreaks in southern Utah and northern Arizona. The United States has already had its worst year of measles cases in more than three decades. There have been 1,958 confirmed cases as of December 16. The last time case counts reached 2,000 was in 1992. Annual infections have exceeded 1,000 only once in the 33 years between 1992 and 2025—when infections reached 1,274 in 2019.
Measles researchers and epidemiologists predict the virus will continue to spread in transmission chains possibly linked to the West Texas outbreak that began in January. If that occurs, the country could lose measles elimination status—an achievement secured 25 years ago marking the end of uninterrupted measles spread. The status is mainly a technical designation, but its loss would reflect backsliding in the public health fight against one of the most infectious diseases on earth and comes at a time when Trump administration officials are casting doubt on the safety of vaccines and pursuing an overhaul of the childhood immunization schedule.
“We do still have a large number of people in quarantine, and we expect that we will see further cases from those currently in quarantine,” Linda Bell, South Carolina’s state epidemiologist, said in a briefing last week. The Spartanburg outbreak has resulted in 144 infections as of Friday, and 224 people are in quarantine, which lasts for 21 days. Most of the transmission in the Spartanburg outbreak has occurred in household or school settings, and thanks to the virus’s 11- to 12-day incubation period, quarantine numbers have served as a leading indicator of additional infections. Infections have been almost entirely among unvaccinated individuals, with a majority being young people between 5 and 17 years old.
Nationwide, the Centers for Disease Control and Prevention report that measles vaccination coverage among kindergarteners is quite high, at 92.5 percent for the 2024-25 school year. The South Carolina outbreak has followed a pattern similar to other U.S. outbreaks over the last 25 years, taking hold in communities with concentrations of unvaccinated or undervaccinated individuals. More than three dozen public and private schools in Spartanburg County have vaccination rates below 90 percent for state-required immunizations, including the measles, mumps, and rubella (MMR) vaccine. The county has the highest rate—8.2 percent–of religious exemptions from school vaccine requirements in the state.
Many of the cases have occurred in a Ukrainian and Eastern European immigrant community; the virus has circulated in a Slavic-language church and surrounding schools where rates for required immunizations, including the measles vaccine, are well below the 95 percent threshold needed to interrupt the spread of the virus. Global Academy, a public charter school attended by many students from the Ukrainian community, was one of the first schools to see cases. Just 21 percent of students at the academy have the required vaccinations.
Dr. William Moss, an infectious disease epidemiologist and pediatrician at Johns Hopkins University, told The Dispatch that it’s challenging to predict the trajectory of measles cases, but if large outbreaks continue into next year, he said it would look a lot like what we have seen in 2025. He likened the spread to an initial forest fire casting off sparks. “Those sparks are infectious individuals, and they travel to other communities,” he said. “If one of those sparks lands in another community where there’s a larger proportion of unvaccinated or non-immune individuals, then we tend to get this larger outbreak.”
“It’s connectivity between communities and then the relative susceptibility within those communities,” he added.
It’s possible that 2025’s flames could simply burn themselves out, but the greater the size and quantity of the fires, the more likely the country could experience a sustained spread of the disease and spikes among vulnerable clusters of people. While there have only been a handful of large outbreaks in 2025, 43 states have had one or more measles cases, and there have been 49 outbreaks of three or more related cases. Last year, there were only 16 outbreaks, and only 30 states had cases.
Epidemiologists and researchers warn that endemic spread of measles could possibly return in the coming decades. A modeling study published in the medical journal JAMA earlier this year estimated that the U.S. could experience more than 800,000 measles cases over the next 25 years if current vaccination rates in each state hold constant. Significantly, the study projected that if vaccination rates increased by just 5 percent, there would be fewer than 6,000 cases over the next quarter century.
“Our 2025 JAMA study and recent measles outbreaks have all suggested that the U.S. is on a tipping point for measles returning to becoming commonplace,” Dr. Nathan Lo, a Stanford researcher who co-authored the study, told The Dispatch.
But in the near term, Moss said that widespread transmission throughout the country is unlikely to emerge given the high level of population immunity. “We’re not going to go back yet to where we were in the prevaccine era or in the ’60s and ’70s,” he noted, “but we will probably have more frequent and larger outbreaks.”
The Pan American Health Organization (PAHO), a regional branch of the World Health Organization, monitors and evaluates the elimination designation for countries in the Americas, including the U.S. in cooperation with national public health authorities. The assessment is based on a totality of indicators about whether endemic or sustained measles transmission is occurring. A country can in theory maintain its elimination status while experiencing multiple independent outbreaks so long as there isn’t a continuous chain of transmission for 12 consecutive months. Trump administration officials have emphasized that there is no evidence yet definitively linking the West Texas outbreak, which was declared over in August, to other ongoing outbreaks.
But it can be challenging to find definitive proof given the genetic similarities of the virus circulating not just in the U.S. but also Canada and Mexico. The regional concentration of outbreaks in the southwest, Moss argued, suggests that in the absence of definitive evidence, the outbreaks are likely linked. “The burden of proof is going to be on those who claim that this is not one large outbreak, that this is really several smaller outbreaks,” he said, adding that he expects there to be some debate over the technicalities if PAHO revokes the U.S. elimination status next month.
“Elimination status depends on evidence of continuous transmission for 12 months, and our current assessment is that we have not met that criteria,” a spokeswoman for the Department of Health and Human Services said when The Dispatch asked if the agency anticipates losing elimination status next year. Canada officially lost its elimination status last month; the country has had 5,000 cases this year.
Ultimately, the designation is just that, and holding onto the status in January does not mean measles will become more or less prevalent in the coming years. “Whether we formally lose that elimination status, to me, isn’t even that important in the sense of we already know we’ve got a terrible, terrible problem on our hands,” Michael Osterholm, the director of the Center for Infectious Disease Research and Policy at the University of Minnesota, told The Hill.
Public health officials and doctors continue to emphasize that vaccination is the best way to stem the tide of new and ongoing outbreaks. Two doses of the MMR vaccine in advance of exposure is 97 percent effective at preventing the disease. But receiving the vaccine within 72 hours after exposure can also still help protect against severe illness.
Bell, the South Carolina epidemiologist, said she hopes people understand how vaccination enabled the country to end common measles transmission and how that historic success now contrasts with the picture in Spartanburg. “We are faced with ongoing transmission that we anticipate will go on for many more weeks, at least in our state,” she said, “and that could be avoided.”
