Hours after the Centers for Disease Control and Prevention recommended COVID-19 booster shots for tens of millions of Americans, President Joe Biden on Friday urged those who are immediately eligible to again roll up their sleeves.

The CDC has recommended third doses for anyone who received their second Pfizer-BioNTech shot at least six months prior and is 65 or older, has underlying conditions or works at a job that puts them at an increased risk of being infected.

“My message today is this: If you got the Pfizer vaccine in January, February or March of this year and you’re over 65 years of age, go get a booster,” Biden said in a speech from the White House’s State Dining Room. “Of if you have a medical condition like diabetes or you’re a front-line worker, like a health care worker or a teacher, you can get a free booster now.”

Biden said 20 million Americans are eligible immediately to receive booster shots. He said the extra shots will again be available for free at more than 80,000 locations, including over 40,000 pharmacies.

Biden said he will receive his booster shot “as soon as I can get it done.”

“It’s hard to acknowledge I’m over 65,” the 78-year-old president joked. He was given his second Pfizer dose in January.

Regulators have not yet authorized booster shots for the Moderna and Johnson & Johnson vaccines. 

Biden also had a message for people who received those vaccines.

“You still have a high level of protection,” he said. “Doctors and scientists are working day and night to analyze the data from those two organizations on whether and when you need a booster shot, and we'll provide updates for you as the process moves ahead again.

“Bottom line is if you're fully vaccinated, you’re highly protected from severe illness, even if you get COVID-19.”

Some health experts accused Biden of exerting pressure on the Food and Drug Administration and CDC last month when he announced a plan to start offering booster shots of the Pfizer and Moderna vaccines before regulators had an opportunity to review the data and debate the matter. 

The president, however, defended the process Friday. 

“The decision of which booster shot to give, when to start the shot and who will get them is left to the scientists and the doctors,” Biden said. “That’s what happened here. While we waited and prepared, we bought enough booster shots, and states and pharmacies, doctors’ offices and community health centers have been preparing to get booster shots in arms for a while.”

Biden again cast his ire for the prolonged pandemic on those Americans who refuse to get vaccinated.

As of Thursday, 55% of Americans have been fully inoculated, and 75% of those who are eligible — ages 12 and up — have gotten at least one shot.

“But one quarter has not gotten any (shot),” Biden said. “In a country as large as ours, that 25% minority can cause an awful lot of damage, and they are causing a lot of damage.

“The unvaccinated overcrowd our hospitals, overrunning emergency rooms and intensive care units, leaving no room for someone with a heart attack or a cancer operation needed to get the life-saving care because the places where they would get that care are crowded, they are not available,” he continued.

Biden also blamed the unvaccinated for slowing the country’s economic recovery and costing people jobs.

He also cited reports of unvaccinated people on their death beds saying they wish they had gotten the shots. 

“They’re leaving behind husbands and wives, small children, people who adore them,” he said. “People are dying and will die who don't have to die. It is not hyperbole to suggest it's literally a tragedy. Please don't let this become your tragedy.”