Pfizer testing antiviral pill to treat covid-19: How effective is it? When could it be available?

Drugmakers are racing to find an easy-to-use treatment that could keep people infected with covid-19 from becoming seriously ill or even prevent them from developing symptoms. Three pharmaceutical companies are in mid-to-late-stage clinical trials to test an oral antiviral drug for covid-19.

Pfizer announced on Monday that it began Phase 2 and 3 clinical trials to assess the safety and efficacy of its oral antiviral pill for the prevention of confirmed covid-19 infection and its symptoms. It joins the pharmaceutical companies Merck partnered with Ridgeback Biotherapeutics and Atea in collaboration with Roche in testing potential antiviral therapies for covid-19 in clinical trials.

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What are antivirals?

Antivirals help treat and prevent viral infections in different ways depending on the type. Once a person is infected, they can be used to reduce the symptoms or the length of time that it takes to overcome the viral infection by boosting the immune response. They can also be used as a preventative measure to block receptors so virus can’t latch onto healthy cells or lower the risk of an infected person from spreading a virus.

They are already used to treat HIV, herpes and the flu. One of the most widely known antiviral drugs is Tamiflu, used to prevent serious ailment or hospitalization from the flu. But antivirals are not a substitute for a vaccine when one is available according to the CDC.

Currently, there is only one antiviral that has full FDA approval and is available to patients diagnosed with covid-19, Gilead Sciences’ Remdesivir. Unlike the three other antivirals in clinical trials now, Remdesivir is administered intravenously but scientists are working on an oral version which is still in the preclinical trial phase.

How effective are the antivirals?

So far, the results from all three antivirals in clinical trials have shown that they are well tolerated and are effective at reducing a patient's viral load. Right now the top contender is Molnupiravir from Merck and partner Ridgeback Biotherapeutics. Atea Pharmaceuticals in collaboration with Roche are testing AT-527 and began Phase 3 trials in April. The Phase 1 results from Pfizer show promise but the data is limited at this time until the drugmaker can perform larger scale trials. Remdesivir, while its oral version is still in the pretrial stage has been showing promise too.

How soon could the oral antivirals be available to the public?

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Results from the Molnupiravir phase 3 clinical trials should be available within the next few weeks according to Merck CEO Robert Davis. This month he said the company could seek Emergency Use Authorization from the Food and Drug Administration before the end of the year. The Biden administration has already agreed to procure 1.7 million treatment courses once Molnupiravir receives Emergency Use Authorization.

Data from clinical trials of the oral antiviral from Atea Pharmaceuticals and Roche are expected later this year.