The Centers for Disease Control and Prevention (CDC), on Thursday, batted for booster shots for millions of older and vulnerable Americans, ushering a new phase in the vaccination drive in the United States against the deadly COVID-19.

CDC Director Dr. Rochelle Walensky signed off on a series of recommendations from a panel of advisers late Thursday.

The officials said that boosters should be offered to people who are aged 65 and older. The booster shots will be extended to nursing home residents and those ages 50 to 64 who have underlying health conditions.

The extra dose would be given once they are at least six months past their last COVID-19 shot.

However, Walensky decided to make one recommendation that the panel had rejected.

The panel had voted against saying that people can be administered the booster shot if they are aged between 18 and 64 and are health care workers. This extended to the people who have jobs that put them at increased risk of being exposed to the coronavirus.

But Walensky disagreed and put that recommendation back in, noting that such a move aligns with an FDA booster authorization decision earlier this week.

“As CDC Director, it is my job to recognize where our actions can have the greatest impact,” Walensky said.

“At CDC, we are tasked with analyzing complex, often imperfect data to make concrete recommendations that optimize health. In a pandemic, even with uncertainty, we must take actions that we anticipate will do the greatest good.”

All of the three COVID-19 vaccines that are used in the US are still highly protective against severe illness, hospitalization and death as the threat of the delta variant looms. But only about 182 million Americans are fully vaccinated, or just 55% of the population.

The third dose of the Pfizer and Moderna COVID-19 vaccines have been authorised by the US for certain people with weakened immune systems. These include cancer patients and transplant recipients.

(With inputs from Associated Press)