In a location kept secret from the public for the past five years, people have injected themselves with drugs more than 10,000 times without dying from an overdose, researchers revealed this week. The findings come amid an opioid epidemic that has killed 400,000 people in the past two decades and a soaring number of overdoses during the coronavirus pandemic.

The success of the safe injection site has prompted calls for policymakers to start considering solutions that focus on reducing harm and deaths rather than traditional law enforcement and punishment. Experts say they fear that if the country doesn’t intervene, this year will bring a wave of fatalities driven by pandemic-related isolation, unemployment and changes to the drug supply.

Operators of the supervised injection site say that over the course of five years, 10,514 injections and 33 opioid-involved overdoses, they have never needed to call paramedics to revive any of their clients.

The site allows people who take drugs to be watched over by trained staff members who are equipped with naloxone, which can reverse the effects of an opioid overdose, said Alex H. Kral, lead author of the study. The research — published Wednesday in the New England Journal of Medicine — is the most comprehensive look at how such an operation can safely operate in the United States. Similar operations have continued to run in 11 counties, including Canada, without any reported overdose deaths.

And the results provide data clarity as lawmakers consider measures to allow similar operations in California, Massachusetts and Philadelphia, Kral said.

“We’re doing the work to see what we can learn from it and whether it works or doesn’t work, and then see if it can drive policy in some sort of way,” he said.

The injection site is invitation-only and allows people to bring drugs obtained before entering the facility and to inject them with sterile needles provided by the operation. In a separate room with seating, users can safely stay post-injection for as long as they like.

While the secret site has operated without official scrutiny, the country nearly saw the opening this year of its first sanctioned supervised injection operation, Safehouse in Philadelphia. But two weeks ago, a federal judge, who previously granted permission for the site to move forward, put it on hold.

“The combination of the pandemic and the momentous protests following the killing of Mr. George Floyd make this the wrong moment for another change,” U.S. District Judge Gerald A. McHugh said in his ruling.

Lawmakers in Massachusetts and California are considering measures to legalize supervised injection operations.

The proposal in Massachusetts would authorize the state’s Department of Public Health to open at least two sites as part of a decade-long pilot program.

In California, Assembly Bill 362 would allow San Francisco and Oakland to approve a pilot program in 2026. The measure comes after a comparable bill was vetoed in 2018 by the governor at the time, Jerry Brown (D). In a statement, Brown wrote “enabling illegal and destructive drug use will never work.”

Experts said they hope the newly published findings show such a program can succeed. And they are pushing for other harm-reduction ideas to get wider consideration.

Some experts advocate giving out test strips that would help people who use drugs detect fentanyl, a substance that is fifty times more powerful than heroin and that has become an especially dangerous driver of opioid deaths. Suppliers have increasingly combined older forms of illicit drugs, such as heroin and cocaine, with synthetic opioids, including fentanyl and carfentanil, often without users knowing.

A quarter of overdose deaths during the past 20 years have been from fentanyl, according to a Washington Post analysis of death statistics provided by the Centers for Disease Control and Prevention. And those deaths happened in just the last six years of that two-decade period.

Experts have discovered that test strips developed by drug testing companies for urine tests can be used by to determine the presence of fentanyl. And a few local health agencies and police departments have started giving them to people who use drugs.

For years, similar harm-reduction initiatives — such as needle-exchange programs and distribution of the overdose antidote naloxone, widely known by the trademark name Narcan — were viewed by authorities as controversial because they might imply approval of drug use.

“The problem is so much of drug policy has been linked to the criminal justice system and to stigmatization and marginalization of those who use drugs,” said Robert Ashford, director and founder of a drug recovery center in Philadelphia. That has to change, Ashford and others said, if the country is to make a dent in the trajectory of the opioid epidemic

Nora Volkow, director of the National Institute on Drug Abuse, a federal research agency, said it is also important to understand the effect the pandemic is having on those who use drugs.

Researchers still understand too little about how addiction works and the best ways to combat opioid deaths plaguing the country, she said. And the coronavirus complicates that understanding significantly. “No one knows what the effect will be,” she said, on addiction among teenagers or on overdose death rates.

Many treatment centers are trying telehealth for the first time and figuring out the most effective way to administer addiction medicine and therapy given the realities of the pandemic.

Since the pandemic started, Volkow’s agency has issued almost $4 million for coronavirus-related research on substance use disorders.

“Part of the problem is that we just don’t know how this is going to unfold,” Volkow said. “And we will need to, in order to help those who need it most.”