Researchers said the prison infection rate was "3,251 per 100,000 residents," while the rate for the general population was around "587 cases per 100,000."

Death rates in correctional facilities were three times higher at 39 deaths per 100,000 prisoners compared to 29 deaths per 100,000 in the general population, the analysis found.

And that's just the tip of the iceberg.

"While these numbers are striking, we actually think the disparities within prisons is much greater," said lead author Brendan Saloner, an associate professor in the Department of Health Policy and Management at the Bloomberg School.

Saloner said some prisons are not even reporting cases, and worse, others are not testing inmates.