By Thomas M. Burton

WASHINGTON -- Food and Drug Administration Commissioner Stephen M. Hahn defended his agency's vetting process for Pfizer Inc.'s Covid-19 vaccine, saying a thorough and meticulous review is needed to assure a skeptical public of the vaccine's safety and effectiveness.

In an interview with The Wall Street Journal, Dr. Hahn said his agency has had 150 people working days, nights and weekends in parallel teams to review the test data submitted by Pfizer and German partner BioNTech SE.

The FDA has also scheduled a meeting of an outside advisory committee for Dec. 10 to review the test data, which Dr. Hahn said was another step taken to assure the public amid concerns that the FDA might rush approval.

"We realize there is an issue in the U.S. around vaccine hesitancy. There have been concerns raised about the speed with which Covid-19 vaccines have been developed," Dr. Hahn said. "This will meet our gold standard of safety and efficacy that the American people have come to trust."

Dr. Hahn's comments came on the day that British regulators cleared the Pfizer vaccine for general distribution. A day before, Dr. Hahn had been summoned to the White House by President Trump's chief of staff, Mark Meadows, to explain why the FDA wasn't acting as quickly as the British.

Both men declined to discuss their conversation, but in the interview Dr. Hahn said the FDA was working as fast as it could to confirm that Pfizer's vaccine is as safe and effective as the company has claimed.

Since Pfizer submitted its application for FDA vaccine authorization on Nov. 20, agency vaccine analysts have been looking at questions such as whether there are differences in how different ethnic and age groups respond. The agency has been looking at the results of about 44,000 study patients.

Even though the FDA has sped the authorization process because the Covid-19 pandemic has already killed more than 250,000 Americans, that faster process still will require "clear and compelling evidence of safety and efficacy in at least one Phase 3 [late-stage] clinical trial, " he said.

The companies have said the vaccine is about 95% effective in preventing the coronavirus-caused disease.

The FDA staff have been looking at individual patient data to ask whether its statisticians come to the same conclusions as the companies did. The process is one that "typically would take us months," Dr. Hahn said.

Groups have been working in shifts, nights and weekends, looking in parallel at issues of clinical effectiveness and safety, and of levels of antibodies to confirm the way the vaccine is working.

In addition to its own analysis, the FDA has scheduled the Dec. 10 meeting of the advisory committee of medical experts, and agency officials have said they expect to reach a decision within three to four days after the meeting.

Preparing the agency's analysis and documents to be made public before the meeting has been time-consuming, Dr. Hahn said, but he added that "we felt it was important to have that independent body take a look at it."

Such advisory committees' advice normally is followed by the FDA, though not always. In this case, with efficacy of about 95% and a disease rampant among the public, it would appear unlikely that the FDA wouldn't authorize a vaccine.

A second vaccine from Moderna Inc. also is already under review by teams at the FDA. The advisory panel is scheduled to evaluate that application Dec. 17.

Write to Thomas M. Burton at tom.burton@wsj.com

(END) Dow Jones Newswires

12-02-20 1924ET