Oral Antiviral Pills: A new force in the fight against COVID?

VIRGINIA MAYO/AP

In early November, Pfizer, developer of the BioNTec-Pfizer COVID-19 vaccine, announced the results of the clinical trials of Paxlovid, a newly-developed oral antiviral pill.

Based on two components, a molecule called PF-07321332 and another pre-existing drug called ritonavir, Paxlovid primarily serves as a protease inhibitor. As protease inhibitors, Paxlovid blocks the enzyme protease, which serves to cut apart long, non-functional strands of viral proteins into smaller functional proteins; essentially deploying viral proteins into use. Together, the PF-07321332 serves to block the protease, while the ritonavir serves to prevent the immune system from destroying the PF-07321332 molecules.

Results from placebo-controlled trials, although coming from a relatively small sample size, have been overwhelmingly positive. One trial consisted of approximately 1200 adults from around the world with a confirmed COVID-19 diagnosis. Each individual was given either a dose of Paxlovid or a placebo pill every 12 hours for five days to control error stemming from placebo effects.
In those treated with Paxlovid, only 0.8 per cent (3 of 389) were hospitalized within 28 days compared to 7 per cent (27 of 385) of those with the placebo. Overall, there were no deaths recorded among those who were treated with Paxlovid and ten deaths recorded for those who were treated with the placebo medication.

In mid-November, with the positive test results in hand, Pfizer sought emergency use authorization from the FDA. Although Paxlovid has yet to be approved by the FDA, they have approved another similar oral antiviral COVID-19 pill called Molnupiravir by Merck.

Molnupiravir, a polymerase inhibitor, operates in a slightly different manner to Paxlovid. Rather than preventing viral protein from splitting into functional proteins, Molnupiravir acts by causing viruses to be more prone to mutations, ultimately creating so many mutations that the virus is unable to survive. The approval of oral-based antiviral pills presents a promising future in humanity’s efforts against COVID-19.