Texas officials have confirmed 561 cases so far this year.
The measles outbreak that started in Texas this year is likely larger than the reported numbers, a U.S. Centers for Disease Control and Prevention official said on April 15.
“We do believe that there’s quite a large amount of cases that are not reported,” Dr. David Sugerman, a senior CDC scientist working on measles, said during a meeting with the agency’s vaccine advisory panel.
“In working very closely with our colleagues in Texas, in talking with families, they may mention prior cases that have recovered and never received testing, [and] other families that may have cases and never had sought treatment,” he said. “So we do think that there is under-testing and therefore under-diagnosis and under-reporting.”
The outbreak in Texas started in Gaines County in January and has since expanded to multiple other jurisdictions, including part of New Mexico.
As of April 15, Texas has confirmed 561 cases, and New Mexico has confirmed 63 cases.
Most patients are either unvaccinated or have no documented doses of a measles, mumps, rubella (MMR) vaccine more than 14 days before the onset of symptoms. Seventeen of the patients had received at least one MMR vaccine dose.
In Gaines County and surrounding areas, falling vaccination rates have been recorded for years. Federal and local health officials say 95 percent coverage is needed for herd immunity, or community protection. But just 82 percent of kindergartners and 90 percent of seventh graders in Gaines County had received two doses, or a full series, of the vaccine, according to the most recent data available, from 2023 to 2024.
Underreporting cases of measles “is not uncommon in close-knit communities that may also have lower health care seeking behavior at baseline,” Sugarman said on Tuesday.
Two people have died from measles in Texas, according tostate health officials. Dr. Edwin Jose Asturias, a panel member, said that factoring in the reported number of cases, the case fatality rate would be much higher than is historically known for measles outbreaks.
“I don’t want to think that there is a higher mortality there. Perhaps what’s happening is a huge amount of under-reporting of the cases of measles that are happening in that jurisdiction,” he said, prompting Sugarman’s comments.
Sugarman reported to the committee that as of April 10, 712 cases of measles have been confirmed across 25 states in 2025—up from 285 cases in all of 2024—with most of the cases being part of one of five ongoing outbreaks.
