Pfizer’s Phase 2/3 study will evaluate the drug candidate in participants who live in the same household as a person who has a confirmed COVID-19 infection.
Participants will also receive ritonavir, an antiretroviral typically used to treat HIV.
The randomized, double-blind, and placebo-controlled study will enroll up to 2,660 healthy adults aged 18 or older, according to Pfizer. Half of the participants will be randomly assigned to receive the drug candidate and ritonavir, while the other half will get a placebo. Both groups will take either the drug or a placebo twice daily for five or 10 days.
The primary objective of the study is to determine whether the drug is safe and whether it can prevent COVID-19 infection through 14 days following exposure to the CCP virus.
“If successful, we believe this therapy could help stop the virus early—before it has had a chance to replicate extensively—potentially preventing symptomatic disease in those who have been exposed and inhibiting the onset of infection in others,” Dr. Mikael Dolsten, chief scientific officer for Pfizer, said in a statement.
Pfizer started a study in early September using the same drug, but participants in that study must have COVID-19 and not require hospitalization.
Pharmaceutical companies Merck and Roche are also competing to develop antiviral pills against COVID-19.
The only COVID-19 antiviral approved or authorized for use in the United States is remdesivir, produced by Gilead Sciences. However, remdesivir is applied through intravenous therapy and has been linked to severe side effects, including kidney disease.