Vaccinations against Covid-19 in the U.S. will “hopefully” start in less than three weeks, according to the head of the federal government’s program to accelerate a vaccine.

“On the 11th or on the 12th of December, hopefully the first people will be immunized across the United States, across all states, in all the areas where the state departments of health will have told us where to deliver the vaccines,” Moncef Slaoui, head of the government’s Operation Warp Speed, said on CNN’s “State of the Union” on Sunday.

Current plans envisage another milestone around May: a 70% immunization rate across the U.S., which “would allow for true herd immunity to take place,” said Slaoui, a former head of GlaxoSmithKline’s vaccines operation. “Most people need to be immunized before we can go back to a normal life.”

While an effective vaccine is expected to be widely distributed in the U.S. in 2021, hurdles remain. An advisory panel of the Food and Drug Administration is meeting on Dec. 10 to discuss emergency use authorization for a vaccine candidate. Pfizer Inc. and BioNTech SE have requested that authorization for their product.

“While we can’t predict how long FDA’s review will take, the agency will review the request as expeditiously as possible, while still doing so in a thorough and science-based manner, so that we can help make available a vaccine that the American people deserve as soon as possible,” FDA Commissioner Stephen Hahn tweeted on Sunday.

With daily infections hovering around record levels , the U.S. reported 1,446 virus-linked deaths Saturday to cap a week of rapidly rising death rates. Only about half of adults say they would get a Covid-19 vaccine, according to a Pew Research Center survey in September.

Anthony Fauci, the U.S. government’s top infectious disease specialist, said achieving herd immunity is possible, though he didn’t think that was likely by May.

“If you get an overwhelming majority of people vaccinated, with a highly efficacious vaccine, we can reasonably quickly get to the herd immunity that would be a blanket of protection for the country,” Fauci said on CBS’s “Face the Nation.”

Slaoui said on CNN “it would be better” if President Donald Trump’s administration formally allowed the presidential transition to begin.

Even so, the operation “has been isolated from the administration, from the political environment, and the political context,” Slaoui said on NBC’s “Meet the Press.”

“All decisions are made, the train is running,” he said. “Whether one administration or the other doesn’t, frankly, make a difference.”

Information on the program isn’t been shared with Joe Biden’s incoming administration, he said, consistent with Trump’s failure to acknowledge his election loss.

“I have been informed that I should not be saying anything that’s confidential to anybody, including, you know, anybody that’s not part of the administration, and therefore, I’ll act according to what the legal requirements are.”

Hospitals are filling up across the country and even in the best-case scenario, state governments will struggle to get the rampaging virus under control amid a chaotic transfer of presidential power and a lack of clear policy guidance. Making matters more challenging is the lack of confidence many Americans have in the safety of a vaccine.

Covid-19 deaths in the U.S. are running at the highest level since last spring, when the outbreak in New York and the northeast pushed deaths to a daily peak of more than 2,600 in late April.

Larry Merlo, chief executive officer of CVS Health Corp., said on CBS that once a Covid jab is approved, “48 hours after we receive that vaccine” the pharmacy company will be in long-term care facilities “providing that vaccine into the arms of our elderly.”

—With assistance from Steven T. Dennis.

This article was provided by Bloomberg News.