More than one in 10 of Northern Ireland prison officers are self-isolating, the Stormont Justice Minister has said.
Prisoners with symptoms of coronavirus have also been identified and are self-isolating within the prison system, Naomi Long revealed.
Ms Long said as of Tuesday, there were 165 prison officers in self-isolation.
"A considerable number," she said given Northern Ireland has about 1,000 prison officers.
"Closed communities at present are incredibly vulnerable because once the virus gets into the prison it will make it incredibly difficult to stop the spread," she said, speaking to BBC Good Morning Ulster.
All prison visits have been suspended to stop the spread of the virus and new approaches are being taken within prisons, she said.
"Many of our prison officers have to self-isolate at the moment because they or their families may have symptoms of the virus.
"Some of those will now be returning to work."
Of the prisoners showing symptoms, she said the number is "relatively small". Those prisoners are being dealt with in isolation units.
"We are very conscious that this is a stressful time for prisoners, their regime is changing, things like education and training, have had to be withdrawn," she said.
"The vast majority of prisoners are working very closely with the prison service because they realise that this is in their best interest."
Ms Long said the prison population was being reduced to deal with Covid-19, including fewer committals to prison because of the outbreak.
People are also being released on bail instead of serving remand sentences. Ms Long said this decision is only being taken "under very strict conditions where it doesn't threaten public safety".
She said the early release of prisoners to reduce the prison population was "not imminent".
It was revealed the UK Government is considering releasing some offenders from English and Welsh prisons to ease pressures.
"We're not there yet" Ms Long said.
She said If it got to the point where prisoners had to be released, it will be done "on the basis of releasing those who are at least risk to public safety and re-offending and also people who are at least risk to themselves".
"Bearing in mind many of our prisoners have mental health issues, have underlying health conditions but also have history, for example, of self-harming," she said.
"There's absolutely no point in us transferring pressure from the prison service back out into the general health service or out into, for example, into the probation service," she added.
"We have to manage this very carefully to make sure public safety is maintained and that we don't overwhelm our prison service and that we're also able to keep all those in our care safe and look after them."