REUTERS: CVS Health and Walgreens  expect to administer the first Pfizer COVID-19 vaccines to residents of long-term US nursing homes on Dec 21, executives at the companies said.

That will be followed by shots from Moderna Inc about a week later, they told Reuters.

Pfizer and BioNTech could receive emergency authorization for their COVID-19 vaccine from regulators as soon as Friday. Moderna's regulatory process is about a week behind.

Officials have said that Pfizer and the US government will begin distributing the shots within 24 hours of receiving a regulatory green light, and hospitals are planning to give healthcare workers the first shots early next week.

CVS expects to receive its first Pfizer dose allotment toward the end of next week but will wait until December 21 to give shots, said Chris Cox, senior vice president at CVS Health. He said US officials want to allow time for the companies to review information documents about the shot and get waivers from nursing home residents and their families.

Some states are opting to use Moderna's COVID-19 vaccine to inoculate their nursing home residents rather than the Pfizer shot, he added, saying that earliest date that CVS can administer Moderna's shots is December 28.

Moderna has applied for emergency authorisation and is expected to receive it soon after a meeting of advisors to the US Food and Drug Administration on Dec 17.

CVS and Walgreens Boots Alliance Inc, which run the nation's largest pharmacy chains but also offer other offsite pharmacy services, have an agreement with the federal government to vaccinate nursing home residents across the country through a voluntary program.

Cox said he believed all states had opted into the federal program, and CVS Pharmacy said more than 40,000 long-term care facilities had selected it as their COVID-19 vaccination provider.