Pfizer Inc. Chief Executive Officer Albert Bourla said that a key safety milestone had been reached in the study of its COVID-19 vaccine, and the drugmaker is now preparing to seek an emergency-use authorization from U.S. regulators.

Speaking at a virtual conference hosted by The New York Times on Tuesday, Bourla said the company was preparing to submit its data to the U.S. Food and Drug Administration. Last week, Pfizer and its partner BioNTech SE reported that an interim analysis showed their experimental vaccine was more than 90% effective in preventing symptomatic cases of COVID-19.

"We are preparing now for submissions,” Bourla said at the conference without specifying when it anticipated to file for an emergency use authorization.