Hundreds of COVID-19 diagnoses have been confirmed at local, state and federal correctional facilities — almost certainly an undercount given a lack of testing and the virus’s rapid spread — leading to hunger strikes in immigrant detention centers and demands for more protection from prison employee unions.

A week ago, the Cook County jail in Chicago had two diagnoses. By Sunday, 101 inmates and a dozen employees had tested positive for the virus. A nearby Illinois state prison reported a coronavirus-related death on Monday, and Michigan prisons reported 78 positive tests. The Rikers Island jail complex in New York City had at least 167 confirmed cases among inmates by Monday. And at least 38 inmates and employees in the federal prison system have the virus, with one prisoner dead in Louisiana.

“It’s very concerning as a parent,” said William Brewer Jr., whose son is serving time for robbery in Virginia. “He’s in there sleeping in an open bay with 60 other people. There’s no way they can isolate and get 6 feet between each other.”

Defense lawyers, elected officials, health experts and even some prosecutors have warned that efforts to release inmates and to contain the spread of the disease are moving too slowly in the face of a contagion that has so far infected more than 150,000 people in the United States, with more than 2,500 deaths.

“By keeping more people in the jails, you are increasing the overall number of people who contract the virus,” and the demand for hospital beds, ventilators and other lifesaving resources, said David E. Patton, head of the federal public defender’s office in New York City, which represents nearly half of the 2,500 inmates in the city’s two federal jails. “They are playing roulette with people’s lives.”

America has more people behind bars than any other nation. Its correctional facilities are frequently crowded and unsanitary, filled with an aging population of often impoverished people with a history of poor health care, many of whom suffer from respiratory and heart problems. Practices urged elsewhere to slow the spread of the virus — avoiding crowds, frequent hand washing, disinfecting clothing — are nearly impossible to implement inside.

“Even as a visitor,” Brewer said, “if you want to wash your hands, you’ve got to walk out and go into another building to do it.”

The Federal Bureau of Prisons, which holds more than 167,000 people nationwide, has been criticized by its own employees as slow to act. On Friday, dozens of public health experts sent a letter to President Donald Trump urging him to take immediate steps to protect inmates and immigration detainees.

Attorney General William Barr said officials were trying to expand home confinement, as opposed to directly releasing federal prisoners, almost all of whom were convicted of felonies. He ordered an assessment of at-risk nonviolent inmates, particularly those who have served much of their sentence.

But it was unclear how many would qualify under a complex list of criteria. And Barr cautioned that the review would not result in immediate transfers because of the need to ensure that prisoners would not spread the virus once freed.

In Chicago, as the number of positive test results at the county jail have skyrocketed, Sheriff Tom Dart has established a quarantine area for those who have the virus and another one for those showing symptoms who have not tested positive but need to be monitored. The most serious patients are being taken to the hospital.

“Our jails are petri dishes,” said Toni Preckwinkle, president of the Cook County Board of Commissioners, comparing them to nursing homes or cruise ships — both places where the virus has spread rapidly. She said officials are seeking to reduce the jail’s population to 4,000 people, from about 6,000 before the outbreak began. Currently, the population stands at about 5,000. Only inmates accused of nonviolent crimes are eligible for release, she said.

In Cleveland, the legal system was quick to act as the coronavirus took hold in the United States, cutting the county jail population in half, to about 1,000 people, since March 12.

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“Otherwise, once this hits, we’d be crippled,” said Brendan J. Sheehan, the administrative and presiding judge of the Cuyahoga County Common Pleas Court. “We would be releasing people immediately, because we couldn’t have a quarantine.”

Sheehan led an effort to expedite cases for inmates in the jail awaiting trial. The usual protocols — hearings, plea deals, requests for trials — were kept in place, but proceedings that might have taken 60 or 90 days were resolved within two or three.

“I don’t want people to think that we’re opening up the jail doors and letting people go,” the judge said, adding, “We have to protect the public and we also have to protect the safety of the inmate.”

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In New York City, where the jail system’s chief physician warned several days ago that “a storm is coming,” Mayor Bill de Blasio said the city had released at least 650 people by Sunday from Rikers Island, the city’s main jail complex. Most of those inmates were convicted of nonviolent crimes and serving sentences of less than a year. Hundreds more were under review for possible release.

In Los Angeles County, Sheriff Alex Villanueva has embarked on what appears to be the largest U.S. effort to release inmates, freeing 1,700 people this month, or about 10% of the population of one of the nation’s largest jail systems.

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“Our population within the jail is a vulnerable population just by virtue of who they are and where they’re located,” he said.

Villanueva said the releases had been limited to inmates scheduled to be freed in 30 days or fewer. All had been convicted of nonviolent misdemeanors, he said. So far, there are no confirmed coronavirus cases inside the county’s jails.

Deputies in Los Angeles have also been instructed to make fewer arrests, and Villanueva asked the district attorney and courts to delay some criminal proceedings. Arrests in areas patrolled by the Sheriff’s Department have dropped from around 300 a day to about 60 a day.

Jackie Lacey, the Los Angeles County district attorney, said that as a way to remind her prosecutors about the seriousness of the threat to inmates, “I have asked my attorneys to consider the health risks in every decision they make.”

But officials acknowledged that there are concerns about reducing incarceration: About 30% of the county’s jail inmates are homeless and they might be living on the street as soon as they are released, making them at least as vulnerable to the virus as they might be behind bars.

In recent weeks, the city has started to open recreation centers, which were closed to stop the spread of the virus, to homeless people.

“We’re not going to keep them in jail because they don’t have a home,” Villanueva said.

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California has the second-largest prison population in the country, after Texas, and at least 12 California state prison employees have tested positive for the coronavirus. Staff and inmates have also tested positive at correctional facilities in Florida, Texas, Michigan, Pennsylvania, New York and Washington, among others, and advocates said there are almost certainly many undetected cases across the country.

Unlike county jails, where most inmates are either serving sentences for minor crimes or are awaiting trial, state prisons — which hold the majority of the nation’s 2.3 million incarcerated people, most of whom were convicted of felonies — are less likely to make large-scale releases.

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For families of incarcerated people, the concern can be agonizing. At other times, Brewer might worry about his son getting into a fight or running afoul of gangs in the Virginia prison system. But now, he just prays he won’t get sick.

Virginia’s Department of Corrections said it has not had any positive tests and it has halted visits to prisoners as a way of trying to keep the virus out. Many other states, as well as the federal prison system, have also limited or halted visits.

In New York City, where the Bureau of Prisons said four inmates had tested positive in the city’s two federal jails by Sunday, a lawsuit filed late Friday asked the federal court in Brooklyn to order the immediate release of about 540 federal prisoners there identified as “particularly vulnerable” to the virus because of their age underlying health conditions.

Katie Rosenfeld, a lawyer for the plaintiffs, said prisoners and their family members were “terrified” that the jail would “very soon be overwhelmed with hundreds of people sick and dying inside.”

Even before the suit was filed, prosecutors in Brooklyn had been directed to review their cases and decide whether releasing inmates would be appropriate, considering their age, health status, the nature of the charges against them and their risk to the community.

Marilyn Mosby, Baltimore’s chief prosecutor, is going through a similar exercise, but has also announced that she will decline to prosecute certain low-level cases, including trespassing, drug possession, prostitution and urinating in public, during the coronavirus outbreak.

“The thing that we’re concerned with is public safety,” she said, “and we don’t want to prescribe someone with substance-use disorder to a death sentence.”

This article originally appeared in The New York Times .