President Joe Biden announced Wednesday that his government will require all nursing home workers to be vaccinated against Covid-19, the latest move to protect Americans if the Delta variant spreads.

“Today I announce a new step,” said Biden in a speech at the White House. “If you work in a nursing home and care for people on Medicare or Medicaid, you also need to get vaccinated.”

Biden’s remarks came after an administrative official confirmed to NBC News that the government will withhold federal funding from nursing homes that don’t fully vaccinate their employees.

The new policy, which would hold back funding for Medicare and Medicaid nursing homes that fail to comply, could go into effect as early as next month, the official said, although the timing is fluid. This would affect around 15,000 nursing homes, which employ more than 1.3 million people nationwide.

The move comes as the highly contagious Delta variant is causing a surge in new cases nationwide, and federal officials say they are starting to see signs of declining vaccine protection against mild and moderate illnesses.

According to data compiled by Centers for Medicare & Medicaid Services, roughly 60% of nursing home workers nationwide are vaccinated – much less than the 82.4% of residents who received the vaccinations. In some states, the percentage of nurses who have been vaccinated is even lower.

Some medical experts have asked the U.S. government to pressure nursing homes to vaccinate their staff, saying the unvaccinated staff put older residents at greater risk, who are more likely to become seriously ill or have something called a breakthrough infection.

“We have to go faster. So I’m taking vaccination measures where I can, ”Biden said in the speech.

The new rules for nursing homes are “all about keeping people safe and safe,” he said.

“This is no time to let our vigilance down. We just have to finish the job, with science, with facts and with confidence,” said the president.

Earlier in the day, federal health officials announced that they plan to provide booster shots to most Americans from the week of September 20th. They said it was “very clear” that immunity decreased after the first two doses, and with the dominance of the Delta variant, “we are gradually seeing signs of decreased protection against mild and moderate illnesses.”

“Based on our latest assessment, current protection against serious illness, hospitalization and death could decline in the coming months, especially for those at higher risk or who were vaccinated during the earlier stages of vaccination,” said the statement signed by CDC director Dr. Rochelle Walensky, Acting FDA Commissioner Dr. Janet Woodcock, White House Senior Medical Advisor Dr. Anthony Fauci, and other US health leaders.

Nursing home residents, health care providers, and the elderly – the first groups to be vaccinated in December and January – will be targeted, according to Dr. Francis Collins, director of the National Institutes of Health, likely prioritized to get extra vaccinations.