The United States has lost its measles elimination status, ending a run of 26 years. The Pan American Health Organization (PAHO) revoked the designation after finding that the same strain of measles has been spreading continuously in the country for more than 12 months.

The decision was first reported on 13 November 2026 and relayed by Reuters the following day. PAHO itself had not published its own formal determination when the reports appeared, and a formal announcement was expected on Tuesday 17 November. The status is a formal designation, not a claim that every person in the country is at high risk. Its loss is an official recognition that measles is once again spreading on its own inside the United States, rather than arriving only in travellers from abroad.

What the loss of US measles elimination status means

A country is said to have eliminated measles when the virus has not spread locally for a year or longer and disease tracking is strong enough to catch cases. The United States earned that status in 2000, when the Centers for Disease Control and Prevention (CDC) counted just 85 measles cases in the whole year. Losing it does not mean the vaccine has stopped working, and it carries no formal sanctions. It means the chain of local transmission has not been broken for over a year.

Measles is the most contagious virus known to medicine. It spreads through the air when an infected person coughs or sneezes, and it can linger in the air for up to two hours after they leave a room. Our earlier explainer, Measles Is Back: Why the Most Contagious Virus Finds Every Gap, sets out how the virus exploits gaps in coverage.

How the decision was reached

PAHO asked all 35 member states in the Americas to submit measles status reports for review by its Regional Monitoring and Re-Verification Commission, a panel of eight independent experts. The commission met in Washington for three days, ending on 13 November, and examined epidemiological and laboratory evidence submitted by the CDC, including genetic evidence that the same virus lineage had kept circulating for more than 12 months.

That finding is the decisive one. A country can keep its elimination status while imported cases arrive, provided each one is contained. Once the same strain is shown to be passing from person to person without a break for a full year, the transmission is counted as re-established, and the status goes. PAHO Director Jarbas Barbosa makes the final call on each country's status.

The 2026 outbreak in numbers

CDC figures reported on 13 November put the 2026 total at at least 5,182 confirmed measles cases, reported from 45 states, New York City and the District of Columbia. That already passes the whole of 2025, when 2,289 cases were recorded, and makes 2026 the worst year for measles in the United States since 1991, when 9,643 cases were recorded. Reuters reported that some 7,500 people have been infected and 13 have died since 2025.

State health departments have reported at least 10 measles-associated deaths in 2026: seven in Pennsylvania, two in Wisconsin and one in New York. The CDC's own official count lists six, because it counts deaths from verified mortality records, a slower process; the agency says its figure is subject to change.

Two more deaths were reported by Pennsylvania and Wisconsin on Friday 13 November, taking the state-reported total from eight to ten. Nearly all of the cases have been in people who were not vaccinated or whose vaccination status was unknown — about 96 in every 100 diagnoses, according to CDC data reported the same week.

Why Pennsylvania is at the centre

Pennsylvania is the hardest-hit state in the outbreak, with 1,542 confirmed cases — the most of any state — and seven of the ten deaths reported in 2026. Large outbreaks have also been recorded in Texas, Utah and South Carolina, and genetic evidence linked those outbreaks to the same virus lineage, which is what allowed the commission to conclude that transmission had continued without a break.

Wisconsin has recorded 651 cases this year, its highest total in more than 35 years. The pattern is the same in each hotspot: coverage has fallen below the level needed to stop the virus, and then months of steady spread have followed.

What the vaccine does, and what it does not

Two doses of the measles vaccine provide 97% protection against the disease. A population needs about 95% vaccination coverage to keep measles from spreading — the level known as herd immunity, which protects the small number of people who cannot be vaccinated for medical reasons. When coverage slips below that line in a community, the virus finds the unprotected and keeps moving.

The vaccine cannot undo the cases that have already happened. What it can do is break the chains of transmission that cost the United States the status.

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What happens next

PAHO's formal announcement is expected on Tuesday 17 November. To win the status back, the United States must interrupt endemic transmission and then remain free of an outbreak for at least 12 months, while submitting a remedial plan to PAHO and strengthening immunisation, surveillance and response.

The United States is not alone. Canada, Spain and the United Kingdom have also recently lost measles elimination status after review by World Health Organization experts. The pattern is the same in each case: vaccination coverage drifting down, then a strain finding enough unprotected people to keep circulating for a year.

The CDC updates its measles figures weekly; the number to watch is the length of the longest unbroken chain of transmission. Until that chain is broken and stays broken for a year, the status stays lost.

What our records show, and what they miss

Our records show how this story built up. We covered the return of measles in October 2026, before the elimination question reached PAHO's commission, and we have tracked the 2026 United States outbreak as the case total climbed past 5,000. The pattern in our records is consistent: the largest outbreaks sit in the states and communities where vaccination coverage has fallen furthest.

What our records miss is the detail that only official weekly updates can supply. They do not carry live state-by-state case counts, which change weekly, and they do not settle the gap between the CDC's official death count of six and the ten deaths reported by state health departments — a difference of counting method, not of fact. They also do not yet carry PAHO's published determination, expected on 17 November, which will fix the formal wording.

The short version

  • PAHO has revoked the United States' measles elimination status, ending a 26-year run since 2000, after finding the same strain spreading continuously for more than 12 months.
  • At least 5,182 measles cases have been confirmed in the United States in 2026, from 45 states, New York City and the District of Columbia — more than double the 2,289 recorded in 2025.
  • State health departments have reported at least 10 measles-associated deaths in 2026, seven of them in Pennsylvania; the CDC's official count lists six, because it uses slower verified mortality records.
  • Two doses of the measles vaccine provide 97% protection, and about 95% coverage is needed for herd immunity. Canada, Spain and the United Kingdom have also recently lost elimination status.
  • To regain the status, the United States must end transmission and stay outbreak-free for at least 12 months; PAHO's formal announcement is expected on 17 November.