Drugmaker Pfizer announced Friday that its experimental antiviral COVID-19 pill cuts the risk of hospitalization and death by nearly 90%.

What You Need To Know

  • Pfizer announced Friday that its experimental antiviral COVID-19 pill cuts the risk of hospitalization and death by 89% in a late-stage clinical trial

  • Patients who received the drug, in conjunction with another antiviral called ritonavir, shortly after showing COVID-19 symptoms had an 89% reduction in their combined rate of hospitalization or death after a month

  • Study participants were unvaccinated, with mild-to-moderate COVID-19, and were considered high risk for hospitalization due to health problems like obesity, diabetes or heart disease

  • Pfizer says it will seek regulatory review from the U.S. Food and Drug Administration (FDA) and international regulators as soon as possible

Pfizer released preliminary results Friday of its study of 775 adults. Patients who received the drug, combined with another antiviral called ritonavir, shortly after showing COVID-19 symptoms had an 89% reduction in their combined rate of hospitalization or death after a month, compared to patients taking a placebo. Fewer than 1% of patients taking the drug needed to be hospitalized and no one died. In the control group, 7% were hospitalized and there were seven deaths.

“We were hoping that we had something extraordinary, but it’s rare that you see great drugs come through with almost 90% efficacy and 100% protection for death,” Dr. Mikael Dolsten, the company's chief scientific officer, said in an interview.

The treatment consists of 30 pills given over the course of five days, including 10 ritonavir pills. The ritonavir slows down the breakdown of Pfizer's pill, known as PF-07321332, and allows it to remain in the body longer. (If authorized, the Pfizer pill would be known as Paxlovid.)

“Today’s news is a real game-changer in the global efforts to halt the devastation of this pandemic," Pfizer CEO and Chairman Albert Bourla wrote in a statement. "These data suggest that our oral antiviral candidate, if approved or authorized by regulatory authorities, has the potential to save patients’ lives, reduce the severity of COVID-19 infections, and eliminate up to nine out of ten hospitalizations."

Study participants were unvaccinated, with mild-to-moderate COVID-19, and were considered high risk for hospitalization due to health problems like obesity, diabetes or heart disease. Treatment began within three to five days of initial symptoms, and lasted for five days. Patients who received the drug earlier showed slightly better results, underscoring the need for speedy testing and treatment.

Pfizer reported few details on side effects but said rates of problems were similar between the groups at about 20%.

"Given the continued global impact of COVID-19, we have remained laser-focused on the science and fulfilling our responsibility to help healthcare systems and institutions around the world while ensuring equitable and broad access to people everywhere," Bourla added.

The data has not yet been peer reviewed, but Pfizer will submit results for review and publication. The company said that an independent board of experts monitoring the trial recommended that it be stopped early because it proved so effective; the practice is standard procedure when interim results show such a clear benefit.

Pfizer says it will seek regulatory review from the U.S. Food and Drug Administration (FDA) and international regulators as soon as possible.

The only other antiviral approved by the FDA – remdesivir, sold under the brand name Veklury – is administered intraveinously. 

The news comes one day after regulators in the United Kingdom granted conditional approval to a similar oral antiviral COVID-19 treatment from Merck. The FDA is convening a meeting of its advisers to discuss the pill in late November.

The Associated Press contributed to this report.