At 5 p.m. ET Thursday, President Joe Biden will unveil his six-pronged strategy to stop the spread of the delta variant and boost vaccinations.

A source familiar with the president's plans told ABC News that Biden will announce an executive order that will "require all federal executive branch workers to be vaccinated," as well as a second executive order that will direct that standard to be applied to employees of contractors working with the federal government.

A White House official said Biden's plan will be centered around:

White House Press Secretary Jen Psaki told MSNBC Thursday, "He wants to lay out the steps we're taking to build on what we did over the summer: more requirements for federal workers, for private sector employees as well. More testing to ensure we know who has COVID and who might spread it. Making sure small businesses survive. That's what you'll hear the president talk about today."

The United Kingdom’s medicines regulator has declared both the Oxford/AstraZeneca vaccine and the Pfizer vaccine as “safe and effective” booster doses.

Dr. June Raine, chief executive of the Medicines and Healthcare products Regulatory Agency, said in a statement, "It will now be for the JVCI [Joint Committee of Vaccination and Immunisation] to advise on whether booster jabs will be given and if so, which vaccines should be used."

-ABC News' Guy Davies

The Los Angeles Board of Education will hold a special meeting on Thursday where they're expected to enact a vaccine mandate for students.

In a meeting with members, the board will propose a resolution that would require all local students at LAUSD school facilities who are eligible to receive the COVID-19 vaccine to become vaccinated and provide proof of vaccination in order to return to the classroom.

The school district -- the second largest in the country, with almost 600,000 students -- has recently welcomed some students back to in-person classes by following strict COVID-19 safety measures, such as constant testing, masking, sanitizing, screening and social distancing.

Schools in the area have also required all staff to be fully vaccinated.

Still, the board said in a statement Wednesday, "COVID-19 remains a material threat to the health and safety of all students within the LAUSD community, and is a further threat to continuous in-person instruction," which is why they are hoping to mandate vaccination among students.

If the resolution is passes, all LA students who are 12 years of age or older, and are part of in-person extracurricular programs, must receive their first vaccine dose by no later than Oct. 3, and their second dose by no later than Oct. 31. Those 12 and older not participating in in-person programs must be vaccinated by November, and "all other students must receive their first vaccine dose by no later than 30 days after their 12th birthday, and their second dose by no later than 8 weeks after their 12th birthday," the board's statement reads.

Kentucky Gov. Andy Beshear announced new grim COVID-19 data and said the state has reached a record high positivity rate of 14.1%, and a hospitalization rate of 2,424.

There are 674 residents in ICUs, Beshear said.

In the last 24 hours, 4,468 newly coronavirus cases and 30 new deaths, including that of a young teen, were reported, according to the governor.

"No matter what age you are, this thing is deadly and it's out there. You need to get vaccinated and you need to wear your mask," he wrote on Twitter.

The Texas attorney general has filed lawsuits against six school districts that mandate masks, the office said Friday.

The lawsuits target the school districts of Richardson, Round Rock, Galveston, Elgin, Spring and Sherman for flouting Gov. Greg Abbott’s executive order prohibiting local entities from requiring masks -- what Texas Attorney General Ken Paxon referred to in a statement as "acts of political defiance."

In a statement to ABC News, Sylvia Wood, a spokesperson for Spring Independent School District, said the district had yet to be served and had no details about the lawsuit beyond a press release.

"Spring ISD will let the legal process unfold and allow the courts to decide the merits of the case," Wood said.

Elgin Independent School District Superintendent Jodi Duron also told ABC News the school district had not been served yet, and that schools in Travis County, part of Elgin ISD, are required to have students wear masks. "To the District’s knowledge, the Travis County Order has not been suspended," she said.

Round Rock Independent School District spokesperson Jenny LaCoste-Caputo told ABC News the school district is following Texas Education Agency guidance that allows for mask requirements "for adults or students for whom it is developmentally appropriate" and is working with local authorities "who advise us that masks remain an essential tool in stemming the spread of COVID-19 in our classrooms."

Sherman Independent School District told ABC News in a statement that it had not received any information on the lawsuit yet and for now "will continue to focus on promoting a safe and healthy learning environment for our students and staff."

ABC News has reached out to the other school districts for comment.

Nearly 90 school districts currently have mask mandates, according to a list compiled by Paxton's office. The attorney general anticipates more lawsuits if school districts "continue to defy state law," his office said in a statement.

Several school districts have sued the state to challenge the ban on mask mandates.

Last week, the Texas Education Agency said it is not enforcing the governor's executive order "as the result of ongoing litigation."