For months, Pfizer CEO Albert Bourla had maintained that the company would know this month whether its BioNTech-shared COVID-19 vaccine works.
Now, finding himself alone in the biopharma world with that bullish estimate, the Big Pharma chief is changing his tone.
"So let me be clear, assuming positive data, Pfizer will apply for Emergency Authorisation Use in the United States soon after the safety milestone is achieved in the third week of November", the company's chairman and CEO Albert Bourla said in an open letter.
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"First, the vaccine must be proven effective, meaning it can help prevent COVID-19 disease in at least a majority of vaccinated patients". This could mean that the study will continue, with half the patients receiving placebo, after it is known that the vaccine is effective.
That's a clear shift from Bourla's previous comments, which constantly featured "October" as the key word-at a time when President Donald Trump was touting a vaccine before the November 3 election, and mentioning Pfizer by name.
"Right now, our model, our best case, predicts that we will have an answer by the end of October", Bourla previously said on the "Today" show. But he added in the letter that the new FDA safety standards would push the company to ask for emergency approval in late November.
"The spread of the coronavirus appeared to be accelerating this week in the US with a key indicator in 44 of the 50 states and Washington, D.C. flashing an "ominous" warning sign", a health official told the Wall Street Journal on Tuesday.
The Food and Drug Administration (FDA), which authorises pharmaceuticals for distribution in the U.S., asked vaccine developers last week to spend two months monitoring for serious side effects after the second dose is given to trial participants. Globally, there have been over 3.92 crore confirmed cases of COVID-19 and over 11.02 lakh people have died so far.
Trump's hopes had been bolstered by Pfizer executives, who have said that they could have clinical trial results sometime in October.
Two injections of BBIBP-CorV at three different doses generated antibodies in all recipients of each group, including older participants, although the data does not prove the vaccine is efficacious, researchers at the CNBG subsidiary, Chinese disease control authorities and other research institutes said in the paper.
On Tuesday, pharmaceutical company Eli Lilly said it paused a government-sponsored antibody treatment trial because of a "potential safety concern".