EXPLAINER: Who must follow Biden's vaccine mandates?

More than half the states are pursuing renewed legal challenges against a requirement from President Joe Biden's administration for millions of healthcare workers across the U.S. to be vaccinated against COVID-19.

The vaccine requirement for Medicare and Medicaid providers was one of several mandates Biden’s administration imposed upon private-sector employers to try to drive up vaccination rates and slow the spread of the coronavirus.

After a Supreme Court ruling allowed it to go forward, the vaccine requirement for health workers was implemented gradually in all states. But opponents are again trying to stop it, arguing among other things that circumstances have changed as cases tied to the Omicron variant have receded.

Two of Biden’s other high-profile orders are on hold. The U.S. Supreme Court blocked a separate rule that would have required employers with more than 100 workers to be vaccinated or tested weekly for COVID-19. A lower court also has blocked a requirement for employees of federal contractors to be vaccinated.

Biden’s various vaccine orders were challenged in court by Republican-led states, conservative groups and some businesses. The lawsuits argued in part that the mandates exceeded federal executive powers and infringed on states’ rights to regulate public health matters.

About 69 percent of the U.S. population age 5 and older is fully vaccinated against COVID-19.

Following is an overview of the Biden vaccine mandates that affect the private sector and the status of the legal fights over them.

HEALTH WORKER MANDATE

What it would do: Under a rule published by the Centers for Medicare & Medicaid on Nov. 5, a wide range of health care providers that receive federal Medicare or Medicaid funding are to require their workers to be vaccinated. The rule affects doctors, nurses,...