President Joe Biden on Thursday 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.