U.S. advisory panel endorses Pfizer-BioNTech vaccine. FDA approval expected to follow

A U.S. government advisory panel has endorsed the Pfizer-BioNTech coronavirus vaccine, in a major step toward an epic vaccination campaign that could finally conquer the outbreak.

Vaccine, infectious diseases experts weighed in on the clinical trial data at day-long hearing

The Pfizer-BioNTech vaccine is being deployed in the United Kingdom, with thousands of doses expected to arrive in Canada shortly. A U.S. panel heard arguments for approval Thursday and endorsed the vaccine, with FDA approval expected to follow. (Dado Ruvic/Reuters)

A U.S. government advisory panel endorsed widespread use of Pfizer-BioNTech's coronavirus vaccine Thursday, putting the country just one step away from launching an epic vaccination campaign against the outbreak that has killed close to 300,000 Americans.

Shots could begin within days, depending on how quickly the U.S. Food and Drug Administration (FDA) signs off, as expected, on the expert committee's recommendation.

In a 17-4 vote with one abstention, the government advisers concluded that the vaccine from Pfizer and its German partner BioNTech appears safe and effective for emergency use in adults and teenagers 16 and older.

That endorsement came despite questions about allergic reactions in two people who received the vaccine earlier this week when Britain became the first country to begin dispensing the Pfizer-BioNTech shot.

Despite all the remaining unknowns, in an emergency, "the question is whether you know enough," said panel member Dr. Paul Offit of Children's Hospital of Philadelphia, who concluded that the shot's potential benefits outweigh its risks.

WATCH l Health Canada doctor talks about the approval:

Top health adviser on COVID-19 vaccine approval

3 years ago
Duration 3:32
Dr. Supriya Sharma, chief medical adviser at Health Canada, talks to The National’s Andrew Chang about the approval process for the Pfizer-BioNTech COVID-19 vaccine and which vaccine candidate could be approved next.

The agency's scientific review was a key step — not just for the U.S., but for countries around the world weighing whether to begin using a vaccine.

Teams of FDA scientists scrutinized tens of thousands of pages of technical data provided by the companies, focusing on vaccine effectiveness, safety, side-effects and the manufacturing process needed to ensure the quality and consistency of the doses.

Health Canada has been receiving what it calls a rolling submission of data from the company, paving the way for its authorization in Canada on Wednesday. Britain and Bahrain previously approved it, with vaccinations in the United Kingdom started earlier this week.

2nd vaccine to be reviewed next week

Pfizer has said it will have about 25 million doses of the two-shot vaccine for the U.S. by the end of December. But the initial supplies will be reserved primarily for health-care workers and nursing home residents, with other vulnerable groups next in line until ramped-up production enables shots to become widely available on demand — something that will probably not happen until the spring.

The FDA next week will review a second vaccine, from Moderna and the National Institutes of Health, that appears about as protective as Pfizer-BioNTech's shot. A third candidate, from Johnson & Johnson, which would require just one dose, is working its way through the pipeline. Behind that is a candidate from AstraZeneca and Oxford University.

U.S. health experts are hoping a combination of vaccines will ultimately enable the U.S. to conquer the outbreak.

Experts estimate at least 70 per cent of the U.S. population will have to be vaccinated to achieve herd immunity, the point at which the virus can be held in check.

A group of about two dozen outside experts weighed in on the FDA's findings. The panellists had expertise in vaccines, infectious diseases and medical statistics.

All eyes now turn to the FDA staff scientists who will make the final decision on whether to press ahead with widespread use of the Pfizer-BioNTech vaccine. FDA's vaccine director Dr. Peter Marks said ahead of the expert meeting that a decision would come within "days to a week."

Vaccine hesitancy an issue

While the vaccine is more than 90 per cent effective in blocking the symptoms of COVID-19, the FDA's advisers stressed it is not yet clear whether it can stop the silent, symptomless spread that accounts for up to half of all cases.

"Even though the individual efficacy of this vaccine is very, very, very high, you really as of right now do not have any evidence" that it will lower transmission, said Dr. Patrick Moore of the University of Pittsburgh. He urged Pfizer to take additional steps to answer that question.

Pfizer must also still show whether the vaccine works in children younger than 16 and in pregnant women.

The deployment of a vaccine would ultimately be up to officials in the 50 states. Some governors and other state officials complained in the spring of a lack of coherence and guidance from the federal government, which resulted in bidding wars for scarce personal protective equipment.

Vaccine hesitancy will also be an issue. About 50 per cent of Americans will take the new coronavirus vaccine, according to The Associated Press-NORC Center for Public Affairs Research survey released this week. About 25 per cent of U.S. adults aren't sure if they want to get vaccinated, taking a wait-and-see approach.

READ | FDA briefing document: Pfizer-BioNTech vaccine data:

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With files from CBC News

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