With inmates and staff members now testing positive for COVID-19 in local jails and state and federal penitentiaries, a humanitarian crisis is looming.

The social distancing that public health professionals are advocating — staying six feet apart to limit the spread of disease — is functionally impossible inside of a prison. “People refer to cruise ships as petri dishes, but nobody has invented a more effective vector for transmitting disease than a city jail,” a former New York City corrections commissioner told ABC News.

Perhaps the most troubling case of all is New York’s Rikers Island. The jail’s first case of COVID-19 was announced on March 18. By Tuesday morning, there were nearly two hundred confirmed cases.