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Pfizer said Thursday it now intends to start human tests on a potential drug to treat Covid-19, the disease caused by the novel coronavirus, in August or September, three months sooner than it previously thought possible.

That would still leave months more research before the medicines could reach patients, but it represents a significant acceleration of the traditional drug development timeline.


The New York-based drug giant also said that it was making new data available on an old antibiotic, azithromycin, to help researchers study it as a potential Covid-19 treatment. It’s also initiating studies of its arthritis pill Xeljanz as a potential treatment for hospitalized patients with the disease and conducting studies to see whether the bacteria S. pneumoniae, which is targeted by its vaccine Prevnar, poses a risk to patients or health care workers who are infected with or will be exposed to coronavirus.

“Given that this is the most threatening pandemic in a century, affecting human health in an unprecedented manner and disrupting society and business, we have mobilized our capabilities across multiple fronts,” said Mikael Dolsten, Pfizer’s chief scientific officer.

The endgame, Dolsten said, would be “a vaccine that can protect our population and expel the virus from the soil of America and back to the empire of bats.” (The coronavirus originated in other species, with bats as a likely culprit.) Pfizer is developing a vaccine, which is completely separate from its drug efforts, with partner BioNTech.


Dolsten said human tests of the BioNTech vaccine should start this month, a timeline it had already disclosed. Pfizer will also try to shorten the timelines of a year or more before that product could become available, at least to high-risk first-responders, such as health care workers or firefighters. The vaccine is one of several in development. Like one leading candidate from biotechnology firm Moderna, Pfizer’s vaccine candidate uses an until-now untested technology that would produce a vaccine using messenger RNA, a genetic material used inside human cells.

He said Pfizer would aim to turn “months to weeks, weeks to days, and days to hours” in attempting to deliver on the vaccine.

On Thursday, Pfizer and BioNTech announced said they will work together to scale up manufacturing capacity before efficacy results will be available. Also, BioNTech will receive an upfront payment from Pfizer of $185 million, including an equity investment of approximately $113 million. In the future, it could be eligible to receive payments of up to $563 million for the vaccine work.

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The treatment that Pfizer is testing, along with several backup compounds, is what is known as a protease inhibitor, a type of antiviral medicine that blocks a key enzyme viruses need to replicate. It was based on a series of compounds Pfizer had previously developed against the virus that causes severe acute respiratory syndrome, or SARS, which is related to the new coronavirus. Pfizer said that several compounds had blocked an enzyme used by the new coronavirus, SARS-CoV-2, and that the lead compound appeared to have antiviral activity in a cell culture.

Such medicines would be given intravenously. Dolsten expressed optimism that if other medicines, such as Gilead’s remdesivir, were to prove effective, patients might benefit from combinations of antiviral medicines, as they do in diseases such as HIV and hepatitis C.

Still, Dolsten emphasized that the risks of drug and vaccine development at this speed are great. In the past, he has likened drug development to a game of chess, where one works out a slow, strategic series of moves. But he said that the battle against SARS-CoV-2 is much more like a game of chance (his example: backgammon), where skill can win the day but rolls of dice play a much bigger part in how quickly success is achieved.

Correction: a previous version of this story misidentified Xeljanz.

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