Pfizer said on Friday that its experimental antiviral pill for COVID-19 has reduced hospitalization and mortality among high-risk adults by nearly 90% because the drugmaker has joined the race for an easy-to-use coronavirus drug.

Currently, most COVID-19 treatments require intravenous injections or injections. Competitor Merck’s COVID-19 pill has been reviewed by the US Food and Drug Administration after showing strong initial results, and the UK became the first country to approve the drug on Thursday.

Pfizer said that after independent experts recommend to stop the company’s research based on the strength of the research results, it will request the FDA and international regulatory agencies to approve its pills as soon as possible. Once Pfizer applies, the FDA can make a decision within weeks or months.

Since the beginning of the pandemic last year, researchers around the world have been racing to find a pill for COVID-19 that can be taken at home to relieve symptoms, speed up recovery and keep people away from the hospital.

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Dr. John Melles, director of infectious diseases at the University of Pittsburgh, said that having drugs to treat early COVID-19 “will be a very important advancement” and he was not involved in Pfizer’s research.

He said: “If someone develops symptoms and tests positive, we can prescribe to the local pharmacy as we treat many infectious diseases.”

On Friday, Pfizer announced the results of a preliminary study of 775 adults. Compared with patients taking fake pills, patients who received the company’s drug and another antiviral drug shortly after the onset of COVID-19 symptoms had a combined incidence of hospitalization or death reduced by 89% one month later. Less than 1% of patients taking the drug required hospitalization, and no one died. In the control group, 7% were hospitalized and 7 died.

Pfizer Chief Scientific Officer Dr. Mikael Dolsten said in an interview: “We hope we have something extraordinary, but it is rare to see great drugs with nearly 90% efficacy and 100% death protection.”

Study participants were not vaccinated, had mild to moderate COVID-19, and were considered to be at high risk of being hospitalized due to health problems such as obesity, diabetes, or heart disease. Treatment started within three to five days of the first symptoms and lasted for five days. Patients who received the drug earlier showed slightly better results, emphasizing the need for rapid testing and treatment.

Pfizer reported few details on the side effects, but said that the incidence of problems between the two groups was similar, about 20%.

The panel of independent medical experts monitoring the trial recommends that standard procedures be stopped as soon as possible when the interim results show such obvious benefits. The data has not yet been released for external review, which is the normal procedure for reviewing new medical research.

Senior US health officials continue to emphasize that vaccination will still be the best way to prevent infection. But because there are still tens of millions of adults who are not vaccinated-and there are many more globally-effective, easy-to-use treatments are essential to curb future waves of infections.

The FDA has held a public meeting later this month to review Merck’s pill, molnupiravir. The company reported in September that its drugs reduced hospitalization and mortality by 50%. Experts warn against comparing preliminary results because of differences in the studies, including the location of the study and the type of variation spread.

“It’s too early to say who won the 100-meter dash,” Melles said. “There is a big difference between 50% and 90%, but we need to make sure that the population is comparable.”

Although Merck’s pills go further in the US regulatory process, Pfizer’s drugs may benefit from safety features that are more familiar to regulators and have fewer red flags. Although pregnant women were excluded from Merck’s trial due to the potential risk of birth defects, Pfizer’s drugs did not have any similar restrictions. Merck drugs work by interfering with the genetic code of the coronavirus, which is a new way to destroy the virus.

Pfizer’s drug is part of a decades-old family of protease inhibitor antiviral drugs, which revolutionized the treatment of HIV and hepatitis C. These drugs block a key enzyme required for the virus to multiply in the human body.

The drug was first discovered during the SARS outbreak that originated in Asia in 2003. Last year, given the similarities between the two coronaviruses, company researchers decided to resume the drug and conduct research against COVID-19.

The United States has approved another antiviral drug for COVID-19, Remdesivir, and approved three antibody therapies that help the immune system fight the virus. But they must be administered intravenously or by injection in a hospital or clinic, and the limited supply was strained by the last surge in delta variants.

Pfizer shares rose more than 8% in Friday morning trading.