Texas Gov. Greg Abbott has tested positive for COVID-19 and is receiving the Regeneron treatment, according to reporter Robert Price.

Abbott is fully vaccinated, according to a news release from Abbott’s office that was shared by Price. Texas first lady Cecilia Abbott tested negative, according to the release.

Abbott, who was vaccinated in 2020, was isolating in the governor’s mansion in Austin, spokesman Mark Miner said in a statement.

The governor is the latest Texan to test positive as cases of the virus soar and hospitals around the state are stretched thin. More than 11,500 patients were hospitalized with the virus as of Monday, the highest levels since January.

The positive test comes a day after Abbott tweeted a picture of himself not wearing a mask while speaking indoors near Dallas to a group of Republicans, most of whom were unmasked.

On Friday, President Joe Biden’s administration offered its full-throated support for local cities and school boards in Texas and Florida that are defying orders by their Republican governors that prohibit mask-wearing mandates in schools.

In a pair of open letters from Education Secretary Miguel Cardona, the administration condemned the orders from Abbott of Texas and Ron DeSantis of Florida which contravene public health guidance from the Centers for Disease Control and Prevention.

Cardona also noted that federal COVID-19 relief funds for schools could be used to fill any financial gaps caused by penalties imposed on local school districts by state leaders.

“The Department stands with these dedicated educators who are working to safely reopen schools and maintain safe in-person instruction,” Cardona wrote.

The two states are experiencing some of the worst COVID-19 outbreaks in the nation, driven by the spread of the more transmissible delta variant among their unvaccinated populations. The two states alone accounted for 40% of hospitalizations from the virus over the last week, the White House said.

Abbott and DeSantis have said they believe parents should decide whether their children wear masks in school. The CDC earlier this month recommended universal mask-wearing in K-12 schools, regardless of vaccination status, to slow the spread of the variant.

Rich Barak of The Atlanta Journal-Constitution contributed to this report.