The debate over mask and vaccine mandates in schools is fueling lawsuits, rapid policy shifts and even sidewalk feuds between parents as students return to classrooms amid a surge in coronavirus cases caused by the more transmissible delta variant.

In Florida, a Leon County circuit judge is due to hear a lawsuit Friday filed by parents challenging an executive order from Gov. Ron DeSantis (R) that prevents school districts from requiring masks. The parents argue that DeSantis’s order violates parts of Florida’s constitution.

Education groups in Arizona sued the state Thursday evening over a ban on mask mandates in schools — a prohibition that the state legislature had passed as part of a budget.

In Texas, Harris County, where Houston is located, defied Gov. Greg Abbott’s ban on mask mandates Thursday by demanding that most schools require face coverings. Local officials in Texas have also sued the Republican governor.

At the U.S. Supreme Court, Justice Amy Coney Barrett rejected a plea from eight Indiana University students to stop the school’s vaccine requirement. Barrett didn’t provide a reason for refusing to block the school’s vaccine decision, in what was the first case about vaccine requirements to reach the high court.

In states such as Alabama and Texas, hospitals are reporting a spike in pediatric covid-19 patients.

Here are some significant developments:

  • A federal advisory panel to the Centers for Disease Control and Prevention voted overwhelmingly Friday afternoon to recommend an additional dose of coronavirus vaccines for some immunocompromised individuals. The move paves the way for millions of moderately or severely immunocompromised people to get a third shot of either the Pfizer-BioNTech or Moderna vaccines as soon as this weekend.
  • Nationwide, 918,000 doses of the vaccines were administered Friday, the most in a single day in more than a month, according to Ben Wakana of the White House’s covid-19 response team.
  • The first large wave of covid-19 cases in children is hitting a swath of low-vaccination states stretching from Florida, South Carolina and Texas, up to Indiana and Missouri — overwhelming hospitals, dominating political debates over mask and vaccine mandates and throwing school reopening plans into disarray. Some front line doctors suggest children are being hospitalized at higher rates and with more serious illnesses.
  • In Florida, DeSantis is vowing to begin dispensing Regeneron monoclonal antibodies — the treatment given to President Donald Trump when he had the coronavirus — through mobile clinics amid a record-breaking stretch of new cases and hospitalizations that have ravaged the state.
  • The U.S. Food and Drug Administration late Thursday authorized booster shots of the coronavirus vaccine for immunocompromised people. Here’s what that means.

Health officials for Harris County, which includes Houston, issued an order requiring masks in “all public and non-religious private schools” and child-care centers, citing a 332 percent increase in coronavirus cases and a 180 percent increase in hospitalizations in recent days.

The county attorney, Christian Menefee, sued Abbott and Texas Attorney General Ken Paxton over the ban on mask and vaccination mandates, saying in a statement that “the current wave of the delta variant presents a real and imminent threat to our most vulnerable populations, and local officials need to be able to respond to this crisis.”

Other local officials in Texas, including in Dallas and Bexar counties, have filed similar lawsuits. A county judge on Tuesday temporarily blocked the state ban, allowing officials in San Antonio and Bexar County to mandate masks.

A spokesperson for Abbott did not immediately respond to a request for comment. In response to similar lawsuits, representatives of the governor have said Abbott “has full authority to issue executive orders that have the full force and effect of law in response to a disaster.”

Yet in Virginia, Gov. Ralph Northam (D) said Thursday that all students and teachers in K-12 schools will be required to wear masks indoors this fall, even if vaccinated, joining a handful of other Democratic governors who have issued similar mandates, in contrast with GOP leaders who have moved to ban them.

“We all share the same goal of keeping our schools open and keeping our students safe,” Northam said a statement Thursday.

County and public school employees in Arlington County will be required to get a coronavirus vaccine or undergo weekly testing, local officials there said Thursday, making it the first local jurisdiction in Northern Virginia to implement such a mandate.

In Georgia on Thursday, parents gathered at the headquarters of the Cobb County School Board, many of them seeking a mask mandate from the board in place of the mask-optional policy it has implemented. But protesters opposing mask mandates were also present, and the two groups clashed. Parents shouted at each other amid accusations of physical blows and spitting, CNN reported.

The Salt Lake County Council in Utah voted Thursday night to overturn a mask mandate that had been issued by the county health director for students in kindergarten through sixth grade. The reversal exemplified the rapidly changing landscape for parents across the country as students face a patchwork of virus-mitigation strategies and rising cases.

Nonetheless, there seems to be some public support for masking in schools. A poll released this week by the Kaiser Family Foundation found that 63 percent of parents of school-age children said their school should require unvaccinated students and staff to wear masks.

In Washington, the head of the White House coronavirus response team, Jeffrey Zients, also noted on Thursday afternoon that the average number of 12-to-17-year-olds getting vaccinated has doubled in the past month as students return to classrooms.

States with the highest virus case rates made the greatest strides in increasing immunizations, he said. The average number of shots given per day almost tripled in Arkansas and quadrupled in Louisiana, Alabama and Mississippi in the past month, Zients noted.

President Biden lashed out Thursday at the politicization of masks in schools. “I know there are lot of people out there trying to turn a public safety measure — that is, children wearing masks in school so they can be safe — into a political dispute,” he said in remarks from the White House. “This isn’t about politics. This is about keeping our children safe.“

Derek Hawkins, Michelle Ye Hee Lee and Steve Hendrix contributed to this report.