Fifteen measles cases — mostly in school-aged children — have been confirmed in a small county in West Texas with one of the highest rates of vaccine exemptions in the state.

South Plains Public Health District Director Zach Holbrooks said Monday that his department was first notified in late January about the first two cases in Gaines County, which he said were “two children who had seen a physician in Lubbock.”

Some of the cases appear to be connected to private religious schools in the district, said Holbrooks, who cautioned that the investigation is ongoing.

“I wouldn’t say they’re all connected, but our teams are looking into exposure sites and the background of those cases,” he said.

Local health officials set up a drive-through vaccination clinic last week and are offering screening services to residents.

The U.S. saw a rise in measles cases in 2024, including an outbreak in Chicago that sickened more than 60. This month, health officials in metro Atlanta are working to contain a measles case that spread to two unvaccinated family members.

Texas law allows children to get an exemption from school vaccines for reasons of conscience, including religious beliefs. The percentage of kids with exemptions has risen over the last decade from .76% in 2014 to 2.32% last year, according to Texas Department of State Health Services data.

Gaines County has one of the highest rates in Texas of school-aged children who opt out of at least one required vaccine: Nearly 14% of children from kindergarten through grade 12 had an exemption in the 2023-24 school year, which is more than five times the state average of 2.32% and beyond the national rate of 3.3%.

But the number of unvaccinated kids in the county is likely significantly higher, DSHS spokeswoman Lara Anton said, because Gaines County has many children who are homeschooled and whose data would not be reported.

The measles, mumps and rubella vaccines is a two-shot series: The first is recommended at 12 to 15 months old and second between 4 to 6 years old. The vaccine is required to attend most public schools in the U.S.

But vaccination rates have declined nationwide since the COVID-19 pandemic and most states are below the 95% vaccination threshold for kindergartners — the level needed to protect communities against measles outbreaks. Lawmakers across the country have proposed various vaccine requirement changes at a time when anti-vaccine activist Robert F. Kennedy Jr. is awaiting confirmation as the secretary of Health and Human Services.

One of the early Gaines County cases traveled to neighboring New Mexico while they were still infectious, Anton said, but there were no immediate reports of infection. New Mexico health officials didn’t immediately respond Monday to a request for comment.

Two cases of measles were reported in early January in the Houston area, but Holbrooks said the West Texas cases don’t appear to be connected.

Measles is a highly contagious virus that can survive in the air for up to two hours. Up to 9 out of 10 people who are susceptible will get the virus if exposed, according to the U.S. Centers for Disease Control and Prevention. Before the vaccine was introduced in 1963, the U.S. saw some 3 million to 4 million cases per year. Now, it’s usually fewer than 200 in a normal year.