How Pfizer made an effective anti-covid pill

In a statement, the World Health Organization said it believes “prevention is better than cure” and that “these drugs will not be alternatives to vaccines.” The organization, based in Geneva, has yet to make a formal recommendation in favor of Paxlovid and says it wants to track whether side effects emerge.

“It’s going to be very hard to use Paxlovid on a wide scale, because people are going to have to be tested and treated very early,” says Robert Shafer, a professor of medicine at Stanford University. “It’s just not going to have the same impact that vaccines will, and it will be a very expensive solution in comparison.” 

A different strategy

Maybe so. But the pills are still an important addition to the anti-covid arsenal.

Early in the pandemic, international organizations plowed billions into vaccine programs. They also gave priority to “repurposing” existing drugs, essentially searching pharmacy shelves for anything that might help. But designing a new, customized chemical drug didn’t get the same kind of public support. “The world seemed to give up on new antivirals before they even started,” Annette von Delft, a researcher at the University of Oxford, wrote in Nature last year. 

Von Delft is part of an organization called Covid Moonshot that says it struggled to find funding for new antiviral pills. That’s despite some big successes with other antivirals, like the pills that keep HIV in check and, more recently, those that conquered hepatitis C. The group says one reason is that health authorities believed designing a new chemical from the ground up would take too long.

It’s true that such an effort involves unavoidable rounds of trial and error. “You can’t give a computer an enzyme and say, ‘Design me a drug for this.’ It might give you 100 ideas, but then you have to synthesize those,” says Michael Lin, a researcher at Stanford University. Synthesizing a single drug can take several weeks, and then you still have to learn its key properties, like whether it’s absorbed in the gut or broken down in the liver. All that is done through real-life tests on animals. 

What’s more, some large drug companies have shifted away from antiviral research in recent years. Despite the successes with HIV and hepatitis C, the list of viruses affecting rich countries—viruses for which there’s no vaccine and where a pill could make money—hasn’t been very long. Academics like Icahn’s White, who is a specialist in influenza drugs, saw their career prospects dimming. “People didn’t think there were any more profitable viruses to treat,” says White. “There was a period there where it was hard to stay in business.”

But, it turns out, the chemists knew a few tricks that proved invaluable against the covid virus.

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