By Madeline Holcombe and Jason Hanna, CNN

(CNN) -- Covid-19 vaccines will be distributed to vulnerable populations within days of any decision to authorize them, an official said, as coronavirus hospitalizations in the US are at an all-time high.

The Food and Drug Administration will meet Thursday to discuss whether to grant emergency use authorization (EUA) for the Pfizer/BioNtech vaccine candidate. A decision could come within days of that meeting, officials say.

And after any EUA comes, "we will start to have shots in arms within 96 hours" of that decision, Gen. Gustave Perna, chief operating officer of the federal government's Operation Warp Speed vaccine initiative, said Tuesday. "That's what I believe with all my heart."

The FDA also intends to deliberate on a separate vaccine candidate, from Moderna, on December 17.

Assuming the vaccines are approved, "20 million people should get vaccinated in just the next several weeks," US Health and Human Services Secretary Alex Azar told CNN on Wednesday.

Governors are prioritizing who would get the vaccines first in their states, though health care workers and the most vulnerable, including residents of long-term care facilities, are expected to be first in line.

As the US anticipated its moves, Canada's health department said Wednesday it approved the Pfizer vaccine for that country, a week after the United Kingdom did the same.

Details from Health Canada were expected to be announced later Wednesday, but Canadian Prime Minister Justin Trudeau said this week that Canada would receive an initial shipment of 249,000 doses by the end of the year and expected Canada's first vaccinations to occur sometime next week.

In the United States, Covid-19 cases, hospitalizations and deaths are soaring.

The US has averaged 206,152 new cases a day over the last seven days -- the country's highest average in the pandemic so far.

And 104,600 Covid-19 patients were reported in US hospitals Tuesday, also a high for the pandemic, according to the COVID Tracking Project.

The country's average number of daily coronavirus deaths across a week -- 2,230 -- is close to the highest-ever average of 2,241 recorded on April 24, Johns Hopkins University data show. In total, more than 286,300 people in the US have died of the virus.

More than 15.1 million official Covid-19 cases have been reported, according to data from JHU, though researchers believe the actual number of infections is much higher.

If vaccine approvals happen as hoped -- including potentially for other manufacturers early next year -- the wider US public could start to see vaccines available in February and March, Azar told CNN's "New Day" Wednesday.

The White House coronavirus task force has warned that current vaccination plans wouldn't reduce the spread of Covid-19 until at least the late spring.

UK asks people with severe allergies to abstain from Pfizer vaccine for now

People with a "significant history of allergic reactions" should not be given the Pfizer/BioNTech coronavirus vaccine, UK health authorities said Wednesday, after two health care workers had allergic reactions after receiving a shot.

The UK, which already has approved the vaccine, began administering it to thousands of people there on Tuesday.

The new precautionary advice on allergies was given after two health care workers "responded adversely" following their shots Tuesday, National Health Service England said Wednesday.

The two recipients had an unspecified history of allergic reactions, and both carried adrenaline autoinjectors. Both are recovering, officials said.

But because of the two incidents, "any person with a history of a significant allergic reaction to a vaccine, medicine or food (such as previous history of anaphylactoid reaction or those who have been advised to carry an adrenaline autoinjector) should not receive the Pfizer BioNTech vaccine," the UK's Medicines and Healthcare products Regulatory Agency said in new advice Wednesday, according to PA Media.

The MHRA said it will issue updated advice once it reviews the two cases. Pfizer issued a statement saying it was supporting the investigation.

Azar, the US health and human services secretary, said he wants to make sure the FDA examined the UK allergic reaction data when it discusses the Pfizer vaccine Thursday.

"FDA is not going to cut any corners," Azar told CNN Wednesday.

People with a history of severe reactions to vaccines were not included in its vaccine trial, according to Pfizer data released by the FDA on Tuesday.

Dr. Paul Offit, a vaccine expert at Children's Hospital of Philadelphia, told CNN that roughly one of every 1.4 million vaccine doses in the US is complicated by a severe allergic reaction.

In the case of the Pfizer vaccine, he said it will be important for UK officials to find out exactly what component of the vaccine caused the reactions in the two patients, so that the country could offer tailored guidance rather than a "blanket recommendation."

US needs to pull together for holiday season, experts say

The impacts of the pandemic are spread across the country, Assistant Secretary for Health and Human Services Admiral Brett Giroir told CNN Tuesday.

Los Angeles County confirmed a total of 8,000 coronavirus deaths and over 3,000 hospitalizations on Tuesday, which the Los Angeles County Department of Public Health called a "tragic milestone" in a news release. And Pennsylvania recorded its highest number of coronavirus hospitalizations Tuesday.

As more holidays approach, it is increasingly imperative that Americans acknowledge the realities of the pandemic and pull together to mitigate its impacts, experts said.

"The end of the pandemic is in sight. The vaccine will work, it will end the pandemic and return us to as near normal or normal as possible, but we have to do our part right now, which is those mitigations techniques," Giroir said.

The US already was recording 40,000 to 70,000 new coronavirus cases daily in September and October, before a severe fall surge picked up in November -- and spread from Thanksgiving gatherings will result "in a surge upon a surge," Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, said.

Families and friends gathering for Christmas and Hanukkah could add another spike to the mix, making impacts of the pandemic even worse in December and January, Fauci said Tuesday in a discussion with the National Urban League.

"We're going to be asking people to do something that is difficult and maybe even painful, particularly at the family level, is to tell people, unless it's absolutely necessary, not to travel," he said. "We said that over Thanksgiving and we're saying the same thing over Christmas."