Moving aggressively to combat the spread of the Delta variant, President Biden announced a six-part plan on Thursday that would touch on nearly every aspect of society, in what amounted to the most expansive use of his presidential authority since he took office in January.

Here is what is in the plan.

Enacting new vaccination requirements

To increase the number of Americans who are vaccinated, the Labor Department will develop an emergency rule requiring all private-sector businesses with more than 100 employees to require that their workforces be fully vaccinated or test negative at least once a week. The rule would affect an estimated 80 million workers. Employers will also be required to give paid time off for employees to get vaccinated.

In an expansion of his earlier push to vaccinate the federal work force, Mr. Biden signed an executive order requiring all executive branch employees and federal contractors to be vaccinated, with no exception to test out of the requirement.

Mr. Biden said he intended to extend a vaccination requirement that applies to health care workers who treat patients on Medicare and Medicaid in nursing homes to all other medical facilities, including hospitals and at-home care.

“The time for waiting is over,” the president said, estimating that the strategy would affect about 100 million Americans, or two-thirds of the work force.

Easing access to booster shots

Mr. Biden pointed to booster shots as a crucial way to continue to protect vaccinated Americans from the coronavirus. Government doctors “believe that a booster is likely to provide the highest level of protection yet,” he said.

The administration has bought the booster shots necessary to give Americans a third shot, and he said the federal government was “ready to administer them as soon as they are authorized.”

It is still unclear when booster shots will be available to the public, and Mr. Biden on Thursday reiterated the administration’s pledge that it would not offer the additional shots until federal regulators backed the proposal.

Last week, top federal health officials told the White House to scale back a plan to offer coronavirus booster shots this month to the general public, saying that their agencies needed more time to collect and review all the necessary data.

Keeping schools free of the virus

Mr. Biden announced a string of measures intended to keep the coronavirus from spreading in schools and infecting children under the age of 12, who are not yet eligible for a vaccine.

For parents, he urged that they ensure children ages 12 and older are vaccinated; for states, he urged mandating school staff and teachers to be inoculated.

Mr. Biden also said that nearly 300,000 educators who work in federally run school programs would be required to be vaccinated.

“About 90 percent of school staff and teachers are vaccinated,” he said. “We should get that to 100 percent.”

While no vaccine has been approved for children under the age of 12, the president said he continued to support the Food and Drug Administration as it worked to approve one “as safely and as quickly as possible.”

The president also slammed efforts by elected officials like Gov. Ron DeSantis of Florida who are dismantling local mask mandates, many of which apply to schools. Mr. Biden said the Education Department was moving to take legal action against those efforts and promised that the federal government would compensate any educator whose pay is withheld “for doing the right thing.”

“Right now, local school officials are trying to keep children safe in a pandemic while their governor picks a fight with them,” he said. “Talk about bullying in schools.”

Increasing testing and masking

As part of a broader effort to bolster the affordability and availability of testing, the president said that his administration had teamed up with retailers, including Amazon and Walmart, to lower the cost of at-home Covid-19 rapid tests.