Non-vulnerable prison staff and inmates at Northern Ireland's jails are yet to get the Covid-19 vaccine.
The chair of the NI Prison Officers' Association has written to the Executive, calling for ministers to act as a matter of urgency.
Prisoners, who have been classed as vulnerable, are currently receiving the jab from the South Eastern Trust, which cares for inmates in prisons here.
However, Ivor Dunne, the chair of the NI Prison Officers' Association, expressed his "extreme disappointment" that both staff and prisoners have not been given the vaccine as a priority - comparing prisons to care homes.
Mr Dunne wrote to First Minister Arlene Foster, Health Minister Robin Swann and Justice Minister Naomi Long earlier this month urging them to vaccinate both staff and inmates as soon as possible.
Almost 30 prison officers, medical staff and inmates had to self-isolate following a Covid outbreak at Magilligan Prison in November, while four prison officers tested positive at south Belfast's Hydebank Wood facility a month earlier.
Last month, two youths also tested positive for the virus in Woodlands Juvenile Justice Centre in Bangor.
Meanwhile, it was revealed by Ms Long in January that 7.5% of prisoners released early due to the pandemic have allegedly reoffended.
Mr Dunne said it was "disappointing" that both prison staff and inmates have yet to be vaccinated because it is hard to know who has an underlying health condition and who does not.
"I am extremely disappointed because prison staff have stepped up to the mark from the start of this pandemic," Mr Dunne said. "Has this question even been posed on the floor of the Assembly that staff should be vaccinated?
"Speaking as the head of the union, I am quite disappointed. Prisons are like nursing homes. Everyone should be vaccinated because you don't know whether a prison officer or a prisoner might have underlying medical conditions.
"With the seriousness of Covid-19 you just don't know what can happen so everyone should be vaccinated as soon as possible.
"Prison staff are key workers and I have written to the Health Minister and the Justice Minister with reference to that."
A spokesperson for the Department of Health said that supply is the main issue holding up vaccination. The current phase of the vaccination programme is focusing on protecting the most vulnerable from Covid-19, such as care home residents and carers, those aged over 50 and individuals with underlying health conditions.
"It is entirely understandable that people in different public-facing occupations want to receive the vaccine as soon as possible," added the department.
"It should be stressed that anyone in these jobs who is clinically vulnerable to Covid-19 will be among those prioritised for vaccination.
"There are tens of thousands of people in public facing occupations in NI. If they are all to receive vaccine prioritisation now regardless of their age or health condition, then many people who are clinically vulnerable will have to wait longer for their jabs."