A milestone the United States has guarded for a quarter-century is now on the line, as global health experts prepare to decide in the coming days whether the country should still be considered measles-free — a designation it has held since 2000.
The review by the Pan American Health Organization (PAHO) puts new pressure on the Trump administration and its leading health official, Robert F Kennedy Jr, who for years has cast doubt on the safety of measles vaccines without scientific evidence.
Public health specialists say policies pursued under Mr Kennedy as US health secretary to reduce the number of childhood immunisations have helped deepen vaccine hesitancy, coinciding with the nation’s highest measles infection rate in more than three decades.
PAHO has requested measles status reports from all 35 member states in the Americas, which will be assessed by a panel of outside experts.
The experts are set to deliver recommendations after closed-door deliberations in Washington, where PAHO’s annual meeting runs until 13 November.
Robert F Kennedy spread doubt about vaccines before becoming US health secretary
Mexico and Bolivia are also being monitored because of extended outbreaks, a PAHO spokesperson said yesterday.
After the panel’s review, PAHO Director Jarbas Barbosa will make the final determination on each country’s status and relay it to the relevant authorities, the spokesperson added.
The outcome is expected to be announced publicly early next week.
“It feels really concerning, as though everything is falling apart. The US was held up as a model for a lot of vaccine programs,” said Helen Bedford, professor of children’s health at University College London, who has advised the UK government on vaccination.
She added: “But measles is definitely back in the United States.
“And it will take a lot of work to reverse that. And it is tragic, because it’s children who are going to suffer at the end of the day.”
The US Department of Health and Human Services said in a statement that national vaccination rates declined before Mr Kennedy took office.
Dr Erica Schwartz, director of the US Centers for Disease Control and Prevention (CDC), said the agency is coordinating with US states to curb outbreaks, concentrating on communities where immunization levels have been slipping for decades.
She said if the US is stripped of its measles-free status “we’re going to be doing the same exact thing that we’ve been doing today”.
That includes “reemphasising that the number one way to prevent measles is the MMR (combined measles, mumps and rubella) vaccine”.
Measles rise in the US
Since President Donald Trump began his second term in early 2025, state and federal health officials have reported nearly 7,500 measles cases in the US, along with 11 deaths.
Measles, a highly contagious virus, typically brings on symptoms such as high fever and a rash, and can also cause severe long-term complications — and in some cases death.
PAHO’s experts will weigh whether measles transmission in the US has continued without interruption for 12 months or longer, drawing on epidemiological and laboratory evidence.
“Whether or not the US loses its measles elimination status, we have a huge problem with measles,” said Noel Brewer, a public health professor at the University of North Carolina who also chairs an independent US advisory panel on measles.
Prof Brewer said he presented the CDC’s measles status report — along with his group’s assessment — to PAHO experts yesterday, but declined to share details.
Even as state and federal officials try to rein in the outbreaks, infections in the US have climbed sharply, more than doubling this year compared with 2025.
Prof Brewer said publicly available information suggests the Arizona-Utah outbreak, which started in June 2025 and is still continuing, likely satisfies that 12-month threshold.
Canada, Spain and the UK have recently had their measles-elimination status removed following reviews by World Health Organization experts.
Although the US has withdrawn from the WHO, it remains part of PAHO, the WHO’s branch for the Americas.
Demetre Daskalakis, a former senior CDC official who resigned after Mr Kennedy took office, said losing measles-free status would signal something larger — a weakening of the country’s public health architecture.
“Measles is the great indicator of where the cracks are in our foundation,” he said.
