MINNEAPOLIS — For the tens of thousands of kids locked up in juvenile detention centers and other correctional facilities across America, experts have issued a gloomy warning: The coronavirus is coming.

Already this week, Louisiana confirmed that a staff member and three children in state custody had contracted the virus, including one living in a group home in Baton Rouge. Minnesota, New York, Texas and Connecticut also have reported positive tests among youth or staff.

Worried about the virus’s spread in crowded facilities, more than 30 correctional administrators and children’s rights advocates called Tuesday for the release of vulnerable youths and for the stoppage of all new admissions. They also want a clear safety plan for those who remain inside, including access to adequate cleaning supplies and contact with loved ones.

“Even though these kids are hidden from view, they are still part of our community and their health affects the health of all of us, as we affect them,” said Renee Slajda, of the nonprofit Louisiana Center for Children’s Rights.

“Imagine what would happen if one school were allowed to stay open, even when students began testing positive for the virus," Slajda said. "Hundreds of people would be exposed — the children, staff, and communities they go home to every night.”

When adults are counted, there are more than 2.2 million people behind bars nationwide, more than any other country in the world. Prisons and jails are considered possible incubators for the virus, with cases multiplying quickly once entering a facility.

At Rikers Island and nearby city lockups in New York alone, the number of cases jumped nearly tenfold to more than 320 in just two weeks, according to the Department of Corrections.

Some states have started releasing inmates at adult facilities, including elderly and others suffering from chronic illnesses.

But little attention has been paid to the 43,000 minors in America’s detention centers and correctional facilities, said Marc Schindler of the advocacy group Justice Policy Institute. He noted that even though COVID-19 has not been hitting large numbers of young people hard, kids may be silent carriers of the virus that causes the disease, and those who are locked up may be at higher risk because they have more health problems than those of the same age in the general public.

For most people, the coronavirus causes mild or moderate symptoms, such as fever and cough, that clear up in two to three weeks. For some, especially older adults and people with existing health problems, it can cause more severe illness, including pneumonia, or death.

They have little or no access to hand sanitizer, masks or other protective gear, said Mary Moran at Our Voice Nuestra Voz in Louisiana, adding that many have preexisting health conditions.

But physical health concerns aren't the only issue with youths.

When he was young, Hernan Carvente Martinez spent time at the Horizon Juvenile Center in New York, where there have already been three confirmed cases, and he still has friends in the juvenile system.

The pandemic carries a heavy emotional toll, he said.

Many educational programs have been cut back or suspended, and visitation from family has been totally cut off in most cases, leaving children feeling isolated and vulnerable. Kids who are locked up already have a far higher risk of suicide than those in the general population, often linked to drug dependency, mental illness or traumatic childhood experiences and frequently involving physical and sexual abuse.

“That in and of itself puts a tremendous amount of hardship on their mental health,” said Martinez, who now works for the Youth First Initiative, a nonprofit that aims to close youth prisons and end juvenile incarceration.

“There is that fear that you’re going to be caught by the crisis and then ultimately have to deal with it while being away from your family and everyone you love.”