Pfizer testing pill that could fight off COVID after exposure or infection

Pfizer is testing an antiviral pill that could fight off COVID-19 infection among people who have a close contact that tests positive for the virus.

In a news release Monday, the biotech company announced the start of a late-stage trial for the drug to test its efficacy against the virus in combination with a low dose of the HIV drug, ritonavir, among those who are at least 18 years old and who live in the same household as someone with a symptomatic COVID-19 infection.

The drugmaker hopes to enroll at least 2,660 people in the double-blind study. Participants will receive either the treatment regimen or a placebo twice each day for five to 10 days.

The study is part of a larger clinical trial launched in March that aims to develop a safe, easy treatment for coronavirus infections after they surface so as to ease the burden on hospitals.

According to CBS News, the drug belongs to a class of medicines called protease inhibitors, which are used to treat diseases such as HIV and Hepatitis C. They work by hampering the production of enzymes needed for the virus to multiply in human cells.

By adding ritonavir in combination with the pill, scientists hope the treatment will last longer in the body.

In March, Dr. Mikael Dolsten, Pfizer's chief scientific officer, said the antiviral treatment could potentially be prescribed "at the first sign of infection, without requiring that patients are hospitalized or in critical care."

Pfizer is also testing the drug among people already infected with the virus. The company expects those results by the end of the year.

"With the continued impact of COVID-19 around the world, we believe that tackling the virus will require effective treatments for people who contract, or have been exposed to, the virus, complementing the impact that vaccines have had in helping quell infections," Dolsten added in a statement Monday.

"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," he said.

Forbes noted there are currently few drugs designed to fight infection among those who either have already contracted the virus or been exposed to it. And the ones that are available — such as monoclonal antibodies — are expensive, scarce, and require administration in a hospital setting.