Measles has spread across nearly all U.S. states since an outbreak began in West Texas in January, with more than 4,300 confirmed cases under the Trump administration — a figure not seen in three decades. The Centers for Disease Control and Prevention is analyzing viral genetic code to determine whether measles has established endemic transmission within the country, which would cost the United States its measles-free status first declared in 2000.
The analysis gained urgency after ProPublica reviewed over 1,800 whole genome sequences comparing measles viruses circulating in the U.S. and Canada. The nonprofit newsroom found that the measles virus still spreading in Utah as of May is very closely related to the strain that sickened Texans more than a year earlier. A panel convened by the Pan American Health Organization will decide the nation's status in November.
What the Right Is Saying
Administration officials argue they are managing a global pandemic not unique to the United States. HHS spokesperson Andrew Nixon said Kennedy "believes Americans deserve clear information about both the benefits and risks of medical products so they can make informed healthcare decisions."
White House spokesperson Kush Desai told ProPublica that critics should examine why "the Trump administration's efforts to contain America's measles outbreak has been so much more successful than those of Canada and Mexico" given those nations' higher per-capita case counts.
Kennedy himself has sought to distance the administration from the resurgence. At a Senate hearing in April, he noted the Texas outbreak began before he became health secretary. "We have a global pandemic," Kennedy said. "It has nothing to do with me."
On Fox News last year, Kennedy acknowledged the vaccine offers protection from measles but emphasized that "there are adverse events from the vaccine" and it "does cause deaths every year." The Infectious Diseases Society of America states there have been no deaths shown to be related to the shot in healthy people.
What the Left Is Saying
Democratic lawmakers and public health advocates say the administration has undermined confidence in vaccines at a critical moment. Senator Elizabeth Warren of Massachusetts said the spread represents a "preventable crisis" driven by mixed messaging from HHS leadership. The Infectious Diseases Society of America published fact sheets noting that researchers worldwide have found no link between the MMR vaccine and autism.
Dr. Adam Ratner, a pediatric infectious disease physician who wrote a book about measles, said Health Secretary Robert F. Kennedy Jr. has done "everything in his power to undermine confidence in vaccines." During an outbreak in New York City beginning in 2018, Ratner treated at least five unvaccinated children who required hospitalization, including some needing intensive care.
"You need a highly vaccinated population to control the spread," Ratner said. "In the absence of that, I think we will have ongoing spread, and we'll have tragedies like the ones we saw in West Texas with the two kids who died." The deaths involved two unvaccinated girls in Texas and an adult in New Mexico.
What the Numbers Show
The CDC declared measles eliminated in 2000 after nearly four decades of immunization programs. Elimination means no continuous chain of transmission lasting more than a year, not zero cases.
Since Trump's inauguration, U.S. measles cases have exceeded 4,300 — the highest total in approximately 30 years, according to public health data reviewed by ProPublica.
ProPublica's genomic analysis identified five genetic mutations present in both Texas and Utah viruses that also appeared in sequences CDC published from infections in Iowa, North Dakota, Minnesota and Alaska during May and June of last year. Dr. Alberto Severini, a retired molecular virologist and measles expert who spent two decades at Canada's Public Health Agency, said the genetic similarity will make it difficult for the U.S. to prove measles is not endemic.
"Unless CDC has something up their sleeves," Severini said, "it's going to be very difficult."
Canada lost its measles-free status last year. No whole genome sequencing from cases in Mexico or Ontario — where measles has also surged — has been made public.
The Bottom Line
The genetic evidence does not constitute proof of endemic spread, as the virus could have traveled abroad and returned via travelers before spreading again domestically. CDC spokesperson said in a written statement that "sequencing alone cannot determine whether transmission has been continuous or sustained."
PAHO invited the U.S. to present its case in April, but American officials requested more time for investigation. The review was rescheduled for November.
Dr. Leisha Nolen, Utah state epidemiologist, said her team could not determine where the first confirmed patient there contracted measles despite reviewing places they had been and people they surrounded themselves with.
While most Americans still support immunization, some states are moving to loosen school vaccine requirements in the name of medical freedom rather than tighten them, according to health policy trackers. The country may find travelers linking U.S. cases to international outbreaks and preserve its designation — but experts say that would only delay a reckoning if vaccination rates do not improve.
"It doesn't change the fact that there's been transmission of measles in the United States for over a year," Severini said. "If people don't vaccinate, measles is going to be endemic."