On a call with investors Tuesday, Pfizer CEO Albert Bourla said that the company doesn't anticipate making any announcement on its trial until about a week after the data and safety monitoring board conducts its review of the company's phase three vaccine trial. The board, which will assess whether its trial with German drugmaker BioNTech has been successful, has not conducted an interim efficacy analysis yet, Pfizer said.
"In case of a conclusive readout ... we will inform the public as soon as we complete the necessary administrative work, which we estimate to be completed within one week from the time we know," Bourla said on the call.
"Let's all have patience," he added. "I know how much the stress levels are growing. I know how much the vaccine is needed for the world."
The phase three trials are a critical last step needed to get the vaccines cleared for distribution. Three other U.S.-backed candidates are in phase three: Moderna, AstraZeneca and Johnson & Johnson. Pfizer expects to apply for an emergency use authorization with the Food and Drug Administration next month.
The board will not conduct its analysis until after there are 32 cases of Covid-19 diagnosed in Pfizer's phase three trial. The board could recommend ending the trial if the vaccine is found to be at least 77% effective, which means it could reduce the risk of getting Covid by 77%.
With no interims conducted yet, Pfizer's "infection rates must be much lower than initially estimated given that they were previously 'confident' of a conclusive answer in October," Brad Loncar, biotech investor and chief executive officer at Loncar Investments, said in a tweet Tuesday.
Since early September, Bourla has repeatedly said the company could have late-stage vaccine trial data as early as October. The timeline drew concerns and skepticism from infectious disease experts and scientists who also feared the process could be influenced by politics, not science. President Donald Trump has insisted a Covid-19 vaccine could be ready before Election Day.
In a phone interview with CNBC's Meg Tirrell later Tuesday, Bourla said his October timeline created some "unintended consequences."
"But I never regret that I follow the guideline that I go with the speed of science," he said. "If the speed of science is telling me end of October, so be it. But it is true that created unintended consequences because some people connected it that to the election."
He reiterated it's unlikely Pfizer will have results ready for release before the election.
"It's not unlikely that we will have events, it is unlikely that given that we are now a week exactly before the election and we don't have anything today, it usually takes up to a week from the day the DMC announces something that we're in a position to make a press release, and given the importance of something like that, it's unlikely that would be before the election," he said.
Earlier in the day, Pfizer said it had enrolled more than 42,000 volunteers in its late-stage trial. It said nearly 36,000 of the volunteers have already received the second of its two-dose Covid-19 vaccine. In September, Pfizer expanded the enrollment of its phase three trial to up to 44,000 volunteers from the initial target of up to 30,000.
The update on the trial came as Pfizer reported a mixed quarter. Third-quarter sales dropped by 4.3%, hurt in part by lower demand for some of its drugs due to the pandemic.
Sales fell to $12.13 billion, down from $12.68 billion a year earlier and lower than the $12.32 billion Wall Street analysts surveyed by Refinitiv were expecting. Still, the company's profits were slightly better than expected at 72 cents per share, higher than the 71 cents analysts were projecting.
The vaccine contains genetic material called messenger RNA, or mRNA, which scientists hope provokes the immune system to fight the virus.