US Loses Measles Elimination Status as Cases Surge to Highest Level Since 1991

A commission of independent experts that reports to the director of the Pan American Health Organization has concluded that the United States no longer qualifies as a country that has eliminated measles. A source close to the process told CNN of the decision on Friday, after The Wall Street Journal first reported it. Measles had held that status since 2000, meaning it was no longer considered a continually transmitting illness in the country.

The ruling was widely expected. The international committee treats measles as endemic when infections from the same strain pass from person to person for at least a year within one country. To test that, members study the genetic code of viruses sampled from patients. Each time the virus copies itself it makes tiny changes, so comparing genomes shows how closely cases are related and whether they belong to the same chains of transmission.

Utah supplied the clearest evidence. In August, scientists at the state's public health laboratory published a preprint showing that one strain had circulated there for more than a year and accounted for over 95 percent of the state's cases. It moved from the southwest of the state to central Utah and caused more than 600 cases between June 2025 and June 2026. Sustained outbreaks have also hit South Carolina, Pennsylvania, Wisconsin and New York, among other states. It is not clear which data the committee relied on, but Dr Angela Rassmussen, a virologist at the University of Saskatchewan and editor-in-chief of the journal Vaccine, said it was not a hard call. The Utah data alone, she said, would have been enough.

The numbers behind the decision are stark. More than 5,400 measles cases have been reported in the US this year, the most since 1991. Most are tied to 43 new outbreaks, though over 1,000 stem from outbreaks that began last year. Nearly all of this year's cases are in people who were not vaccinated with the MMR shot or whose status is unknown. The CDC says roughly one in nine reported cases has led to hospitalisation, and state reports show at least 10 deaths. The country has logged record cases, hospitalisations and deaths for two years running, while some members of the Trump administration, the president included, have cast doubt on the safety and effectiveness of the vaccines.

The country has always had outbreaks since 2000, usually sparked by travellers carrying the virus in. High vaccination rates kept them small and short. Two doses of MMR cut an exposed person's risk of illness by 97 percent compared with someone unvaccinated. In 2025 and 2026, though, the virus reached more unvaccinated families and communities.

Dr Demetre Daskalakis, a former director of the CDC's National Center for Immunization and Respiratory Diseases, called measles elimination a vital sign of the public health system, one that shows cracks in the foundation. Dr Nuwan Gunawardhana, an epidemiologist at Columbia University Irvine Medical Center, said it points toward reversing a generation of progress. Dr Peter Hotez of Texas Children's Hospital called the loss incredibly embarrassing but said the formal status matters less than the fact that measles is pervasive and vaccination rates are down across the country. The nation helped rid the world of smallpox and spent decades driving measles offshore.

The risks fall hardest on infants too young for the vaccine and on people with weakened immunity from organ transplants, cancer or other conditions. Dr William Moss of the Johns Hopkins Bloomberg School of Public Health noted that most people recover after several days of fever, rash and misery, but the infection is not benign. Measles can erase the immune system's memory of past infections, leaving people open to pneumonia or diarrhoea. A pregnant woman can pass it to her baby in the womb, endangering the child's life. Rarely, years later, it can cause subacute sclerosing panencephalitis, a progressive and fatal neurologic disease. Vaccination prevents all of these.

Measles is among the most contagious viruses known: one infected person typically infects 12 to 18 others, and the airborne virus can linger in a room for hours. The US set its first elimination goal in 1978. In 2016 PAHO and the WHO declared all 35 countries of the Americas free of ongoing transmission; Canada lost that status last year, and Mexico, with several large outbreaks, is at risk. Moss says the US must now work toward regaining it, but he calls that hard amid diminished trust in vaccines, rising non-medical school exemptions, falling kindergarten MMR coverage and undermined vaccine policy.