Since the early days of the pandemic, doctors have used the antiviral drug remdesivir to treat severely ill patients hospitalized with COVID-19. A new study suggests doctors could expand its use to treat high-risk patients at home before their symptoms grow worse.

Researchers at several hospitals — including Brigham and Women’s — found that a three-day course of the drug reduced participants’ chances of hospitalization and death by 87 percent.

The research, published Wednesday in The New England Journal of Medicine,arrives just as doctors are facing a shortage of front-line medicines with which to treat patients sick with the Omicron variant, which is resistant to two out of three available monoclonal antibodies. Remdesivir, made by California-based Gilead Sciences, is expected to work well for Omicron because it does not target its highly mutated spike protein. Instead, remdesivir targets the parts that the virus uses to replicate — areas that have fewer genetic changes.

Lead author Dr. Robert Gottlieb, a transplant cardiologist on staff at Baylor University Medical Center in Dallas, said the results could prompt a shift in the way health care professionals treat COVID-19.

A 5- to 10-day regimen of remdesivir is currently administered intravenously to hospitalized patients. But if patients receive a shorter course of the drug sooner, at their homes or outpatient facilities, it could save lives, Gottlieb said.

“If you have the flu, you don’t say ‘let me wait until I’m sicker’ ’’ to take medication, he added.

Catching potentially severe virus cases early could also reduce the burden on hospitals overwhelmed by growing numbers of COVID patients. The strain led Governor Charlie Baker to deploy 500 National Guard members to Massachusetts hospitals and cancel most nonessential surgeries earlier this week.

“If you can keep someone on a trajectory of recovery with remdesivir, rather than have them progress to hospitalization, you can preserve hospital capacity and keep the health care system afloat,’’ Gottlieb said.

The new study involved 562 people who presented at least one risk factor including obesity, diabetes, hypertension, or an age of 60 or older. Of the 279 who received at least one dose of remdesivir, just two, or 0.7 percent, needed to be hospitalized within 28 days. In comparison, the 283-person placebo group saw 15 hospitalizations.

The need for drugs that can prevent COVID-19 hospitalizations has grown increasingly urgent with the spread of Omicron. Two of the three available monoclonal antibody treatments, from the companies Regeneron and Eli Lilly, are useless against the highly infectious and now-dominant variant in the United States. A third antibody treatment that can thwart Omicron, sotrovimab, is in short supply.

On Wednesday, US health regulators authorized the Pfizer antiviral pill Paxlovid, which can also prevent hospitalizations, but it remains in short supply. And on Thursday, the FDA authorized a competing pill from Merck.

“There’s an even more compelling need to have alternative outpatient and effective antiviral therapies,’’ Gottlieb said.

Dr. Paul Edward Sax, the clinical director of the division of infectious diseases at Brigham and Women’s and who was not involved in the remdesivir study, agreed. “Omicron makes the outpatient use of remdesivir suddenly quite relevant,’’ he wrote in an e-mail. “The key thing is that this drug is active, but must be started early. By limiting it to hospitalized patients, we’re missing out on when it’s most effective.’’

“This might be especially useful,’’ he continued, “as a bridge to a time when we have a more plentiful supply of [the Pfizer pill] and/or sotrovimab.’’

In a Dec. 20 blog post about the study, Sax called the results “unequivocally positive.’’

The next step, Gottlieb said, is for the Food and Drug Administration to expand its authorization of remdesivir.

“You don’t win a World Cup tournament by taking only a single shot at the goal,’’ he added. “It’s better to take multiple shots and maximize efficacy.’’

Other experts said remdesivir may also be able to curtail the spread of COVID-19. Patrick Smith, an infectious disease expert and the president of integrated drug development at New Jersey-based biotech Certara, said the drug inhibits the replication of the virus in a patient’s body, reducing the time period during which they are considered infectious.

“That could impact not just the individual person, but the state of spread and public health,’’ Smith said. “A patient taking remdesivir is potentially infecting fewer people.’’

Diti Kohli can be reached at diti.kohli@globe.com.Follow her on Twitter @ditikohli_.