The United States is in the midst of its worst measles outbreak in 35 years, according to official figures released Friday, amid a serious uptick in cases as vaccine hesitancy grows.
Since 2026 began, 2,318 confirmed cases of the highly contagious illness have been recorded, according to the Centers for Disease Control and Prevention.
That surpasses the total for 2025, a year that had already shattered records, with 2,289 cases and three deaths including two young children.
"We are witnessing an avoidable crisis that disproportionally hurts children," said Andrew Racine, president of the American Academy of Pediatrics.
"We should not accept this as our new normal."
Measles causes fever, respiratory symptoms and skin rashes.
In some cases, it can also lead to more severe complications including pneumonia and brain inflammation, which can lead to serious long-term impacts and death.
In 2000, measles was declared eradicated in the United States, thanks to vaccination.
But it has made a strong comeback in recent years against a backdrop of declining vaccination rates and growing distrust in health authorities.
US President Donald Trump's health secretary, Robert F. Kennedy Jr, is accused of contributing significantly to the crisis by spreading anti-vaccine sentiment and fueling fears of well-studied and proven immunizations.
The last time the United States experienced such a high number of measles cases was in 1991, when 9,643 cases were recorded.
Cases began falling dramatically after a two-dose vaccine regimen became the norm.
Prior to the development of a measles vaccine in the early 1960s, measles killed hundreds of children annually in the United States.
It continues to claim tens of thousands of lives worldwide.
- Vaccine skepticism and rising cases -
The current outbreak in the United States has not been contained.
Experts expect the number of cases will continue to rise.
"I definitely believe that there is underdiagnosis," said Melissa Nolan, a professor of epidemiology at the University of South Carolina -- the state that has recorded the highest number of infections this year.
"When you think about the people who are choosing not to vaccinate their children, these are also the people that have medical hesitancy in general," she told AFP.
Although the measles vaccine is mandatory in the US, Americans across much of the country can bypass the rule by citing religious, or sometimes even philosophical, reasons.
Since the Covid-19 pandemic, these non-medical vaccine exemptions have surged, alongside the explosion in vaccine misinformation and distrust of health authorities.
In South Carolina, for example, Nolan said "there is a plethora of places that you can go, and a lot of different social media feeds" that "will walk you through how to do the exemption.
According to a September 2025 poll by The Washington Post and the nonprofit KFF, one in six American parents avoid or delay vaccinating their children over fears of side effects and a lack of trust in health authorities.
The trend is particularly pronounced among white and conservative communities, and is a source of great concern for medical experts.
Nolan says the current outbreak is likely only the beginning.
"Measles is the first one that you tend to see these large outbreaks, because it is the most easily contagious and easily spreadable," she said.
And down the line, "I think we're going to start seeing more and more pertussis cases and just a variety of other vaccine preventable diseases, unfortunately."
