By Devan Cole, CNN

(CNN) -- Moncef Slaoui, the head of the US government's effort to develop a vaccine against Covid-19, on Sunday praised President-elect Joe Biden's plan to ask all Americans to wear masks to curb the spread of the coronavirus, saying the practice is key as the country awaits widespread distribution of the vaccine.

"I think it's a good idea. It's never too late. This pandemic is ravaging the country. We all need to take our precaution, wear our masks, wash our hands, keep our distance, remain aware that this virus is a killer," Slaoui told CNN's Jake Tapper on "State of the Union."

"We have a vaccine. There is light at the end of the tunnel, but we will not all have the vaccine in our arms before May or June, so we need to be very cautious and vigilant," he added.

Slaoui also said he's planning to meet with Biden's transition team this week to discuss plans for how to administer the vaccine to people, something the President-elect said last week that his team hadn't yet seen.

Biden told Tapper in an exclusive interview last week that he will ask Americans to wear masks for the first 100 days after he takes office, though his transition team is treading lightly so far, saying little about how the incoming administration plans to address the plan.

Biden has acknowledged that his authority to enforce a mask mandate is limited and that he will rely heavily on the cooperation of state and local leaders, which may present a challenge in places governed by Republicans, as a number of the party's elected leaders have resisted implementing mask orders amid the worsening pandemic.

Georgia's Republican lieutenant governor told Tapper later in the program Sunday that although Biden's plan is "absolutely a great step in the right direction," mandating mask-wearing "in every single nook and cranny maybe doesn't fit ... reality."

"Certainly I would encourage folks to wear their masks wherever they go, especially in crowds," Lt. Gov. Geoff Duncan said.

The US Centers for Disease Control and Prevention said on Friday that masks are "critical" to controlling the spread of the virus, including sometimes at home.

Vaccine distribution

Slaoui said Sunday that he expects the US Food and Drug Administration to issue emergency use authorization of the vaccine manufactured by Pfizer after a meeting of its Vaccines and Related Biological Products Advisory Committee on Thursday. The FDA has said it is considering EUA, not full approval -- a process that would take months -- for coronavirus vaccines.

"I expect them to recommend approval, based on the data I'm aware of. And I saw the vaccine is highly effective, the vaccine is safe, its safety profile is comparable to that of many other vaccines that have been in use for years," he said.

"Overall, I really hope they do it quickly, and that the vaccine will be available to our population starting later this week," Slaoui added.

While Slaoui used the word approval, what the FDA is considering falls short of full approval. The FDA has said it will require close to full approval standard for a coronavirus vaccine, but will use the quicker emergency use authorization route while the companies pull together all of the information needed for the full approval process, known as a Biologics License Application or BLA.

The agency will meet with the advisory committee again next week to review a vaccine application submitted by Moderna.

Slaoui said that once a vaccine is ready for distribution, it will be administered to health care workers and people in long term care facilities such as nursing homes with the hope that most of them will receive it in the coming weeks.

"Unfortunately, about 40 to 50% of all deaths are happening in the elderly population that's in care homes," he said. "We should be able to have immunized that full population and the health care workers that take care of them by the end of the month of December or by the middle of the month of January."

And by mid-March, Slaoui said, "most of the highly susceptible population -- about 100 million people," should be vaccinated.

CLARIFICATION: This story has been updated to clarify Slaoui's quote on the FDA's consideration of the Pfizer vaccine. It is considering emergency use authorization this week.