The drugmaker moved forward in examining the effects of the oral antiviral candidate PF-07321332 after its first phase of testing determined that the drug was “safe and well tolerated.” In the next phase, Pfizer will recruit up to 2,660 healthy adults who live in the same household as someone with a confirmed symptomatic COVID-19 infection.
Participants will be given the oral medicine and a low dose of the anti-HIV medicine ritonavir to help slow the breakdown of PF-07321332 to keep it in the body longer, or a placebo twice a day for five to 10 days. The protease inhibitor works by blocking the activity of an enzyme that the virus needs to duplicate itself.
The study aims to “assess the safety and effectiveness” of the drug in preventing cases and symptoms of COVID-19 for two weeks after exposure. Pfizer said in a statement that the drug can potentially be given “at the first sign of infection or awareness of exposure without requiring hospitalization of patients.”
Such treatment for COVID-19 exposure has the potential to reduce infections and change the trajectory of the pandemic. Currently, there is no approved oral treatment for people exposed to COVID-19 seeking to prevent infection.
Mikael Dolsten, chief scientific officer of Pfizer, said the company believes that developing treatments for those who catch or are exposed to the virus can help limit infections by “supplementing” vaccines.
“If successful, we believe this therapy could help stop the virus early – before it has had a chance to extensively replicate – potentially preventing symptomatic disease in those who have been exposed and inhibiting the onset of infection in others, ”Dolsten said.
Pfizer’s vaccine, developed with German partner BioNTech, has been the only vaccine approved in the United States to receive full approval from the Food and Drug Administration (FDA) so far. More than 223 million doses have been administered to Americans since its emergency clearance in December, according to data from the Centers for Disease Control and Prevention.