Pfizer announced on Monday that it has launched mid-to-late stage clinical trials for a pill that protects against COVID-19 in individuals at risk of infection. Several companies are working on oral antiviral drugs that can mimic the effects of "Tamiflu" for influenza and prevent the disease from progressing to severe levels. The company’s chief scientist, Michael Dolsten, stated, "We believe that addressing the virus will require effective treatments for those infected or exposed to it, complementing the effects of vaccines."
Pfizer began developing its drug "PF-07321332" in March 2020 and is testing it in conjunction with "Ritonavir," an HIV antiviral drug repurposed for other uses. The clinical trial will involve 2,660 adults who will participate after showing the first signs of COVID or learning of their exposure to the virus for the first time. They will be randomly assigned to receive either a combination of "PF-07321332" and "Ritonavir," or a placebo twice daily for 5 or 10 days. The goal is to evaluate the safety and efficacy of the drugs being studied in preventing infection with the "SARS-CoV-2" virus and the appearance of symptoms by day 14.
Other companies are also testing oral antivirals against COVID, but Pfizer's drug is the first specifically designed for the coronavirus. It is known as a "protease inhibitor" and laboratory tests have shown that it disrupts the virus’s self-replication process. If the treatment proves effective in trials, it is likely to be effective only in the early stages of infection. By the time COVID progresses to a severe disease, the virus has stopped replicating itself, and patients are experiencing an overactive immune response.
