HISD will require masks for all students and staff beginning Monday, Aug. 16. Photo courtesy of HISD.

The Houston ISD Board of Education voted unanimously to back a mask mandate proposed by the school superintendent Thursday night.

The vote was a resolution in support of Superintendent Millard House II’s mandate, which requires masks on all vaccinated and unvaccinated students, staff, and visitors at all schools, on buses, and inside other district facilities.

“The safety of our students and staff will continue to be my guiding compass,” House wrote in a statement released late Thursday. “I am thankful to our Board of Education for supporting our children and families by prioritizing safety above all else.”

HISD’s mask mandate will go into effect Monday. The new school year officially begins Aug 23.

The decision to back the mandate was largely symbolic, as House made clear this week he would move forward with or without board approval. But the unanimous vote was the clearest sign yet that the state’s largest school district was prepared to challenge an order from Gov. Greg Abbott banning such mandates across the state.

The board’s vote came the same day Harris County issued a mask mandate that applied to every school and child care facility in the county regardless of vaccination status. The county also filed a lawsuit seeking to overturn Abbott’s order.

Harris County is just the latest to sue Abbott. Bexar, Dallas and Fort Bend counties have also successfully challenged Abbott’s directive, though the state has appealed the Dallas decision. The issue is expected to be settled in the state Supreme Court.

Meanwhile, the COVID-19 pandemic continues its fourth wave across Texas as the more transmissible delta variant remains the dominant strain of the virus and vaccinations slow. The number of coronavirus hospitalizations across the state is rising sharply, and will likely reach levels last seen during the January peak in the coming weeks.

Abbott has argued that he has broad authority under the Texas Disaster Act to issue bans on mask and vaccine, and stressed personal responsibility rather than government intervention.

Harris County Attorney Christian Menefee told Houston Public Media this week that he acknowledged the governor did have certain powers under the act to suspend laws to help local officials to respond to the pandemic.

But he added that he believed the governor has exceeded the authority granted to him under the act.

“The problem here is that the governor is not using his suspension of laws to respond to the disaster or to help local officials respond to the disaster,” Menefee said. “Instead, he’s using his ability to suspend laws to prohibit local officials from taking action to stop the spread of COVID.”