Southwest measles outbreak continues to grow

Currently, there are around 800 cases of measles in two dozen U.S. states. Many of these cases have occurred in a large outbreak in Texas, which has reported 624 confirmed measles cases since late January. Cases in the neighboring states of New Mexico (65) and Oklahoma (13) are considered to be part of the same Texas outbreak.

During a meeting with state officials, Dan Filardo, leader of CDC's task force for the measles response, said that "[t]his is the largest outbreak in the U.S. since measles elimination was declared in 2000."

Other states reporting double-digit measles cases include Kansas (37) and Ohio (32). In the remaining states that have reported measles, cases are still below 10.

According to CDC, 96% of all the measles cases have occurred in people who are either unvaccinated or whose vaccination status is unknown. In addition, around 70% of measles cases have occurred among children, with a median age of eight.

So far, 85 patients, or around 11% of all cases, have been hospitalized due to measles, with most of these hospitalizations occurring in patients from Texas. There have also been three deaths linked to measles, two confirmed deaths in unvaccinated school-aged children in Texas, and one under investigation in an unvaccinated adult in New Mexico.

Outside of the United States, there have also been severe measles outbreaks in Mennonite communities in Ontario, Canada, and Chihuahua State, Mexico. Canada has reported almost 1,000 cases, and Mexico has reported over 400 cases.

According to Filardo, these outbreaks in Canada and Mexico could also lead to measles spreading in Mennonite communities in the United States.

"With ongoing weddings, large religious gatherings and celebrations to mark the 500th anniversary of Mennonite origins, we remain concerned about the possibility of additional spread of measles across North American Plains communities as the year goes on," he said.

Notably, the percentage of people saying they have heard the false claim that the measles vaccine is more dangerous than measles itself has increased by 15 percentage points since March 2024.

"We looked at statements that we know have been circulating in social media and other arenas. For at least two of these statements, these are things that have been linked to what the HHS secretary has said in public remarks," said Liz Hamel, director of public opinion and survey research at KFF. 

When it came to belief in false claims, most respondents fell into what KFF called the "malleable middle," expressing uncertainty about whether the claims were true or false. More respondents said that the claims were "probably false," but between 16% and 23% said that the different claims were "probably true."

There were also partisan differences in beliefs about these false claims, with Independents and Republicans and those who were Republican-leaning being more likely to say the claims were either "definitely" or "probably" true compared to Democrats. Adults without college degrees, as well as Hispanic adults, were also more likely to say the false claims were definitely or probably true.

According to KFF, believing or leaning toward believing false claims about measles and the MMR vaccine may have impacted parents' decisions to vaccinate their children. Among parents who said that at least one of the three false claims about measles were definitely or probably true, 24% said they had delayed or skipped some recommended vaccines for their children, compared to 11% of parents who said all three claims were definitely or probably false.

"Those parents are more than twice as likely to say that they have delayed or skipped some vaccines for their children compared to parents who don't believe any of those claims," Hamel said.  "I think this is one of the more concerning findings from the poll."

"An erosion in confidence in vaccines down the road could have greater effect," she added. "With something like measles that can be deadly for children, and where you need high levels of vaccination to keep it from circulating, even some of these small increases could have repercussions."