Pfizer released an early snapshot of its Phase 3 trials for its coronavirus vaccine on Monday, and said the results look promising with data suggesting it’s 90 per cent effective at preventing the virus.
The company and its collaborator BioNTech may now be on track to file an emergency use application with U.S. regulators in late November, as previously stated.
However, the announcement does not mean a vaccine is fast approaching, experts warn.
“We aren’t doing terribly well in the fight against COVID-19. The numbers just keep rising in Canada and around the world,” said Kerry Bowman, a professor of bioethics and global health at the University of Toronto.
“This is wonderful news to hear. … Psychologically we needed some good news. However, we have to be quite cautious, as the data is not complete and there are still some lingering questions.”
This is because Pfizer provided only a glimpse of the data and cautioned the initial protection rate might change by the time the study ends.
What does the Phase 3 COVID-19 data say?
Monday’s interim analysis, from an independent data monitoring board, looked at 94 confirmed cases of COVID-19 among the volunteers who had either received two doses of the vaccine or a placebo.
The Phase 3 clinical trial of the vaccine, called “BNT162b2” began on July 27 and has enrolled 43,538 participants — 38,955 of whom have received a second dose of the vaccine candidate as of Nov. 8.
“Approximately 42 per cent of global participants and 30 per cent of U.S. participants have racially and ethnically diverse backgrounds,” Pfizer said in its release.
According to the findings, the trial found that fewer than 10 per cent of infections were in participants who had been given the vaccine, a strong signal of efficacy. More than 90 per cent of the cases were in people who had been given a placebo.
Pfizer said that the vaccine provided protection seven days after the second dose and 28 days after the initial dose of the vaccine.
The company also said that — so far — no participant has become severely ill.
What wasn’t revealed?
“There are still some questions hanging in the air,” Bowman said. “How long does the vaccine work for? We don’t know that, but let’s hope it’s at least one year.”
Bowman said there is also a chance that participants in the trial may have contracted the virus but aren’t showing symptoms.
According to Pfizer, participants were tested only if they developed symptoms, leaving unanswered whether vaccinated people could get infected but show no symptoms and unknowingly spread the virus.
Infection control epidemiologist Colin Furness, an assistant professor at the University of Toronto, said there is still a lot of data that needs to be reviewed. He said he would like to know what the experience was for participants who received the COVID-19 vaccine and still got the virus.
“I would like to know whether or not it was a mild case of coronavirus,” he said. “All of this data should be released, such as the demographics, who got sick, and obviously what the side effects of the vaccine are. Pfizer needs to be very transparent about this.”
The data has yet to be peer-reviewed or published in a medical journal. Pfizer said it would do so once it has results from the entire trial.
Although the data is promising, Bowman said it’s best that everyone remains “cautiously optimistic” as there are still a lot of unknowns.
“We have to be quite cautious. We are looking at public relations from a pharmaceutical company whose primary goal is marketing and profit,” he said. “I am not saying I don’t believe it, but you have to realize that the full data has not been released. They are telling us what the data says, so experts still need to review it.”
But, he said, by the end of November, Pfizer could be publishing more of the results, and then “we will be able to review the larger picture.”
He also stressed the importance of not rushing a vaccine due to “hesitancy” surrounding inoculation.
Because “political interference” could lead to rushing a vaccine, Furness said, companies like Pfizer are aware that “public trust may be shaky.”
“So they have to counter that by being very transparent, let everyone know the data, release all the information,” he said. “Usually pharmaceutical companies want to protect their research. It’s the way of the business … but transparency is very important in this case.”
What comes next?
Pfizer said it doesn’t plan to stop its study until it records 164 infections among all the volunteers, a number that the U.S. Food and Drug Administration (FDA) has agreed is enough to tell how well the vaccine is working. The agency has made clear that any vaccine must be at least 50 per cent effective.
“The study also will evaluate the potential for the vaccine candidate to provide protection against COVID-19 in those who have had prior exposure to SARS-CoV-2, as well as vaccine prevention against severe COVID-19 disease,” the company’s statement said.
The company predicts that its “safety data” following the second and final dose of the vaccine, will be available by the third week of November.
“Based on current projections we expect to produce globally up to 50 million vaccine doses in 2020 and up to 1.3 billion doses in 2021,” the company said (enough to vaccinate 650 million people as it is a double dose).
Canada has signed a deal with Pfizer in August to secure 20 million doses of the coronavirus vaccine in 2021.
Speaking at a media conference on Monday, Prime Minister Justin Trudeau said he hopes to have the vaccine rollout in early 2021.
Bowman said because coronavirus rates are skyrocketing in places like the U.S. and Canada, this means there is a silver lining — more people can volunteer for the trials. He remains optimistic that not only with Pfizer have positive results, but other companies, too.
“This could be very good news, and other vaccines could start working too, so we may have a situation where there is a combination of vaccines or you can ‘take your pick,’” he said.
However, he stressed that despite Pfizer’s promising data, it does not mean that it’s over. It means we are on an “uphill trend,” he said.
“We are not going back to normal life yet. It’s going to take time and research — but boy, did we need this good news.”
— With files from the Associated Press
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