Much of the international scientific establishment was surprised at the move to grant conditional approval and begin vaccinating before the US Food and Drug Administration’s scientific advisory board had weighed in on it and before peer-reviewed studies had been published in international medical journals.

UK Health Secretary Matt Hancock has said that vaccinations will begin next week, starting with vulnerable residents of long-term care homes.

Both the FDA and the EU’s European Medicines Agency (EMA) are taking longer to move on authorizing a Covid-19 vaccine. The FDA’s advisory panel will meet on Dec. 10 to review the Pfizer-BioNTech data and on Dec. 17 to look at vaccine data presented by US biotech Moderna.

The EMA plans to meet on Dec. 29 to decide if there is enough data about the safety and efficacy of the Pfizer-BioNTech candidate to warrant approval, it said in commenting on the UK news. The agency added that a decision on Moderna’s candidate could come as early as Jan. 12.

Pfizer and BioNTech have asked the EU regulator to speed up conditional approval of their vaccine and conclude the rolling review process initiated on Oct. 6. EU Commission President Ursula von der Leyen said EU member states have started working on their vaccination plans and on the logistics for delivering tens of millions of doses, which she said will be “a major challenge.“

The EU backlash against the go-it-alone action of the UK Medicines and Healthcare products Regulatory Agency (MHRA) was pronounced. While the UK’s so-called Brexiteer bloc could hardly conceal its delight in beating the EMA to the finish line and seeing the British population potentially achieve virus immunity ahead of Europeans, some EU leaders said they thought it a rash move for the agency that only became Britain’s top regulatory instance after it quit the European Medicines Agency (EMA).

In the US, top infectious disease expert Anthony Fauci was also critical, suggesting that the UK was “not as rigorous as the US” in its Covid-19 vaccine approval process. “They did not do it as carefully," he told US media, adding, "If you go quickly and you do it superficially, people are not going to want to get vaccinated."

UK health officials begged to differ, saying that the country's vaccine approval process is rigorous and that the vaccine is both safe and effective. "No corners have been cut,” June Raine, head of the MHRA, commented. The agency, she said, had reviewed preliminary data on the vaccine trials dating back to June.

Some outside observers opined that with the UK’s forward thrust the FDA will be under pressure to get the emergency authorization through sooner rather than later. Fauci defended the FDA approach, however, noting that the advisory panel will examine trial reports meticulously.

Approving a new vaccine is a process that would “typically take us months,” FDA commissioner Stephen Hahn told the newspaper Wall Street Journal, “but it could be complete in under a month” after Pfizer’s Nov. 20 filing. 

"The way the FDA is, our FDA is doing it, is the correct way," Fauci told US broadcaster Fox News. "We really scrutinize the data very carefully to guarantee to the American public that this is a safe and efficacious vaccine." He told another broadcaster CBS News, he will meet soon with members of US president-elect Joe Biden's team to discuss the incoming administration's response to the pandemic.

As soon as a vaccine receives the FDA’s conditional approval and Fauci turns thumbs up, three former presidents, Bill Clinton, George W. Bush and Barack Obama, have said they will get the injection themselves – on camera.