Officials began shipping the newly approved vaccine, created by Pfizer and BioNTech, to UPS and FedEx hubs over the weekend. Most sites across states will get doses by Wednesday.
The initial distribution is of 2.9 million doses.
CVS and Walmart personnel are designated with injecting residents in nursing homes, Health Secretary Alex Azar said on CBS' "Face the Nation." Nearly 100 percent of nursing homes have signed up with the program.
"It can start really any day. The vaccines are going out as soon as they receive vaccines," he said.
"According to the governors telling us to ship to them, we could have every nursing home patient vaccinated in the United States by Christmas. It's really a remarkable, remarkable prospect for all of us who have loved ones in nursing homes, that we may approach Christmas with that level of comfort, that our loved ones have gotten some initial protection already."
Chris Cox, senior vice president at CVS Health, had told Reuters that the company wouldn't start administering vaccines until Dec. 21. The company didn't respond to a request for comment.
There are approximately 3 million Americans in long-term care facilities like nursing homes, according to federal data.
Governors can decide whether to adhere to the recommendations or direct the first shots to other populations.
The elderly are one of two groups most at-risk of experiencing severe cases of COVID-19. The other group is people with compromised immune systems, which includes some seniors.
The military is deeply involved in the distribution efforts. Army Gen. Gustave Perna is the chief operating officer for Operation Warp Speed, an all-of-government bid to speed development of COVID-19 vaccines and therapeutics.
"We have an excellent plan that has been well coordinated, well synchronized, well rehearsed, and well collaborated with everybody from the total government through commercial industry down to the governors at the states, I am very confident in it," Perna told reporters on Saturday.
The operation is working with FedEx, UPS, airlines, Pfizer, and McKesson, as well as federal and local law enforcement agencies, to safely and securely distribute and administer the vaccine.
"Because of President [Donald] Trump’s strong leadership and unwavering support for Operation Warp Speed, we have millions of doses of this vaccine that are now being shipped to every corner of America, with administration to begin as soon as providers are ready," Health Secretary Alex Azar said in a statement.