(Reuters) – A panel of outside advisers to the U.S. Food and Drug Administration meeting on Thursday to weigh authorizing Pfizer Inc’s coronavirus vaccine for emergency use were wrestling with when people in the clinical trial who received a placebo should be allowed to get the shots.
The committee is expected to vote sometime after 3:10 p.m. ET (20:10 GMT) on whether the vaccine, developed with German partner BioNTech SE, has shown effectiveness in preventing COVID-19 and if its benefits outweigh the risks.
Documents prepared by the FDA ahead of the meeting did not point out any new safety or efficacy issues, raising hopes the vaccine will soon be authorized in the United States. It has already received regulatory green lights from the UK and Canada.
Pfizer has asked for broad authorization for use of its two-dose vaccine in people aged 16 to 85.
Much of the discussion so far has focused less on whether the vaccine should be authorized, and more on how its emergency use would affect the scientific integrity of the ongoing trial and the way other vaccines are studied in the future.
Once the vaccine is cleared, Pfizer has said it has an ethical responsibility to tell participants if the vaccine is available to them outside of the trial. It has asked the FDA to allow it to give the vaccine to volunteers who had been in the placebo group that request it.
The concern, expressed by both the FDA and members of the advisory panel, is that “unblinding” the trial will make it harder to continue collecting data on long-term safety and effectiveness, and would make it more challenging for companies still testing vaccines to conduct blinded trials, in which people do not know if they got the experimental vaccine or a placebo.
“Once you unblind, you can never go back. We can never collect those data that we need and people want unless you completely redo the whole study,” said Dr. Gregory Poland, a virologist from the Mayo Clinic in Rochester, Minnesota, who has previously served two terms on the FDA advisory panel.
Dr. Steven Goodman of Stanford University School of Medicine said in a presentation to the panel that offering the vaccine to people who got a placebo could result in them “jumping the line,” by receiving the vaccine before they otherwise would under priorities recommended by the U.S. Centers for Disease Control and Prevention.
