Federal prisons, whose inmates may be a high-risk population for a coronavirus outbreak, do not have kits to test for the disease available.

“Once we receive concurrence from local health authorities that a test should be conducted, samples would be collected and sent back to the designated lab for testing,” Federal Bureau of Prisons spokeswoman Nancy Ayers said in an email this week.

Concerns are growing in Congress over how prepared federal prisons are to face any potential coronavirus outbreaks. Experts have long recognized that prison inmates, who live in close proximity to each other and often have underlying health conditions, can be highly susceptible to infectious diseases.

“The risk of community spread poses a critical and unique threat to vulnerable populations, including those in our prisons and jails,” California Democratic Sen. Kamala Harris wrote in a letter to the Bureau of Prisons on Thursday.