At the moment, 10% of staff in a Welsh hospital are using Covid.
Grange University Hospital clinical director Dr Alastair Richards described the situation to be "very difficult" and advised people to avoid it if they can.
This comes just as First Minister Mark Drakeford stated that more than 22% of NHS Wales workers are unable to work due to the virus.
All seven Welsh health boards have reinstated the use masks during hospital visits.
Consultant at Grange University Hospital, Cwmbran. Dr Alastair Richards stated that because people get unwell quickly and often, an emergency ward can go from being full to almost half of its staff.
Dr Richards stated that 10% of the staff are currently off Covid. While this may not sound bad on the surface, it can make management difficult as it often happens at very short notice.
Radio Wales Breakfast interviewed him to discuss the "pressures" facing the entire system and the "very challenging" situation.
"Staff are making very difficult decisions about who they bring in next, who goes in the bed or trolley, and where they will be seen.
"On Monday, nine nurses were added to the emergency ward instead of the usual 25.
He said, "This places a lot of pressure upon the team, and with all the demands we are seeing it makes life very difficult."
He said that although the pandemic has not disappeared, it is currently in a new phase.
"I believe it's about being realistic about where you are heading and if you have symptoms of Covid, then take care of yourself and help others by not going to work or isolating.
"It might not be the law anymore but it is about being good citizens."
Nicky Hughes, associate Director of the Royal College of Nursing, Wales, stated that nurses are exhausted and burned out and hospitals must prioritize what services they provide at this time.
Ms Hughes stated that sickness and vacancies in the system created a lot of pressure on their members. She also said that stress around fuel prices, living costs, as well as the possibility of being in a pandemic for two-and-a half years had all taken a toll on nurses.
She was happy to see that the health boards have taken extra precautions to ensure safety for patients and staff.
"I urge anyone with symptoms to not go to a hospital unless they require hospital care.
"Respect those who go into hospitals asking for masks. It's not about you, it's about protecting your staff and our patients.
Ms Hughes said that while we enjoy more freedoms, Covid has not disappeared.
"We need to be aware that flu can also circulate later in the year. Will we then become susceptible to other strains that could cause serious illness?"
"I believe we need to be fluid. We have to listen to advice and follow the guidance. This includes washing our hands and using face masks, as well as getting our vaccines when given.