WASHINGTON — President Joe Biden is announcing sweeping new federal vaccine requirements affecting as many as 100 million Americans in an all-out effort to increase COVID-19 vaccinations and curb the surging delta variant that is killing thousands each week and jeopardizing the nation's economic recovery.

The expansive rules mandate that all employers with more than 100 workers require them to be vaccinated or test for the virus weekly, affecting about 80 million Americans. And the roughly 17 million workers at health facilities that receive federal Medicare or Medicaid also will have to be fully vaccinated.

Biden is also signing an executive order to require vaccination for employees of the executive branch and contractors who do business with the federal government — with no option to test out. That covers several million more workers.

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Biden is to announce the new requirements in a Thursday afternoon address from the White House as part of a new "action plan" to address the latest rise in coronavirus cases and the stagnating pace of COVID-19 shots that has raised doubts among the public over his handling of the pandemic.

Biden's plans were previewed Thursday afternoon by White House press secretary Jen Psaki and other senior administration officials ahead of the speech.

See 20 Ways America Has Changed Since 9/11

For those of us who lived through 9/11, the day’s events will forever be emblazoned on our consciousnesses, a terrible tragedy we can’t, and won’t, forget. Now, two decades on, Stacker reflects back on the events of 9/11 and many of the ways the world has changed since then. Using information from news reports, government sources, and research centers, this is a list of 20 aspects of American life that were forever altered by the events of that day. From language to air travel to our handling of immigration and foreign policy, read on to see just how much life in the United States was affected by 9/11.