The United States has started to administer the newly-approved coronavirus vaccine produced by Pfizer and BioNTech.

New York State began inoculating heath care workers Monday, with critical care nurse Sandra Lindsay the first to receive an injection.

“First Vaccine Administered. Congratulations USA! Congratulations World!” President Donald Trump said on Twitter.

Super-cooled shipments of the vaccine had rolled out of a Pfizer manufacturing facility in Kalamazoo, Michigan, Sunday for rapid air freight distribution to regional hubs across the United States.

Stephen Hahn, the commissioner of the U.S. Food and Drug Administration, told CNN more than 184,000 vials were on the first trucks leaving the Pfizer vaccine production facility.

Health care workers and elderly people in long-term care facilities will be first in line to receive the first round of 2.9 million doses at a time when cases are surging in the United States.

Meanwhile, President Trump reversed a directive that senior government officials including some White House staff would have access to the first round of vaccines.

In a twitter message late Sunday, Trump said that the White House staff will be vaccinated “somewhat later in the program, unless specifically necessary.” Trump added that he is not scheduled to take the vaccine but looks forward to doing so “at the appropriate time.”

People working in the White House should receive the vaccine somewhat later in the program, unless specifically necessary. I have asked that this adjustment be made. I am not scheduled to take the vaccine, but look forward to doing so at the appropriate time. Thank you!

— Donald J. Trump (@realDonaldTrump) December 14, 2020

The U.S. has recorded more cases than any other country, with nearly 300,000 deaths from the virus and more than 16 million infections, according to the Johns Hopkins University.

Hahn said it is possible that 20 million Americans will be able to get vaccinated with the first of two required doses by the end of December.

The Pfizer coronavirus disease (COVID-19) vaccine arrives at The University of Louisville Hospital in Louisville, Kentucky, Dec. 14, 2020.
The Pfizer coronavirus disease (COVID-19) vaccine arrives at The University of Louisville Hospital in Louisville, Kentucky, Dec. 14, 2020.

Moncef Slaoui, the chief adviser to the government’s vaccine development, told “Fox News Sunday” that 100 million Americans might be vaccinated by the end of March.

But on the ABC News show “This Week,” Hahn said it was a “significant problem” that a quarter to half of Americans, according to polls, are wary of the vaccine produced by the American-German corporate tandem of Pfizer and BioNTech, despite being approved by U.S. health regulators. Others have vowed to not be inoculated.

Hahn said the government has “to be transparent on the safety” of the Pfizer vaccine, as well as on a vaccine produced by biotechnology company Moderna that is being reviewed by regulators this week. Clinical tests showed both were 95% effective.

Slaoui said that for the U.S. to acquire "herd immunity," which would halt transmission of the deadly virus, the country needs about 75% or 80% of the population immunized. He said he hopes that point could be reached between May and June.

"It is, however, critical that most of the American people decide and accept to take the vaccine," Slaoui said. "We are very concerned by the hesitancy that we see."

Governor Phil Murphy of the eastern state of New Jersey told ABC, “We’ve got to deal with a skeptical anti-vaccination bloc” of people.

But he added, “We believe in these vaccines. They’re safe.”

Murphy warned, however, that even as Americans begin to get vaccinated, the coronavirus danger remains daunting.

“The next six to eight weeks are going to be hell,” he said. But Murphy said that by April or May, “everyone will have access to these vaccines.”

Nancy Galloway (L) and Susan Deur cheer as trucks carrying the first shipment of the Covid-19 vaccine that is being escorted by…
Nancy Galloway (L) and Susan Deur cheer as trucks carrying the first shipment of the Covid-19 vaccine that is being escorted by the U.S. Marshals Service, leave Pfizer's Global Supply facility in Kalamazoo, Michigan, Dec. 13, 2020.

The chief officer of Operation Warp Speed, the Trump administration’s vaccine development program, Army General Gustave Perna, said at a news conference Saturday that shipping companies will initially deliver doses to nearly 150 distribution centers, and an additional 450 or so facilities will have the vaccine by Wednesday.

The Food and Drug Administration approved the Pfizer/BioNTech vaccine for emergency use late Friday.

The vaccine must be kept at minus 70 degrees Celsius before being used.