Pfizer confirms possible November coronavirus vaccine application

Pfizer Inc. said it could seek emergency-use authorization for its Covid-19 vaccine in the US by late November if the shot is shown to be effective in a large late-stage trial.

Safety review dictates the timeline, with the Food and Drug Administration requiring that at least half the people in the study be watched for side effects for two months. That milestone should be achieved in the third week of November, Pfizer Chief Executive Officer Albert Bourla said in an open letter published Friday on the company’s website.

“Let me be clear, assuming positive data, Pfizer will apply for emergency authorization use in the US soon after the safety milestone is achieved,” Bourla wrote. An initial readout on whether the vaccine is effective could come later this month, depending on how quickly subjects in the trial -- some of whom got a placebo shot -- become infected with the virus.

Pfizer and its German partner BioNTech SE are on track to potentially be the first to show the efficacy of a Covid-19 vaccine. They and rival vaccine developers are working under a microscope, with almost unprecedented public interest in every detail of their clinical trials. Eli Lilly & Co., Johnson & Johnson and AstraZeneca Plc have had studies of possible vaccines or treatments delayed because of safety concerns.

The letter confirmed a timeline laid out by BioNTech CEO Ugur Sahin this week. The partners haven’t had to stop their late-stage study over safety concerns, Sahin said.