A consultant at the Royal Gwent Hospital in Newport says "around 50%" of his colleagues in A&E have tested positive for coronavirus.
Consultant Dr Tim Rogerson, 40, said a "similar percent" has been affected in the hospital's nursing team.
The frontline doctor revealed the statistic in a video shared by Aneurin Bevan University Health Board - as he revealed that he has tested positive for the virus.
The area is the worst in Wales for cases and one of the worst in the UK.
In the video he explained that he has been off work since experiencing coronavirus symptoms and that his son has also tested positive for the virus.
Dr Rogerson said: "This has obviously happened despite all of the PPE that we've got and all the hand washing that we're doing but it's probably just a likely thing that's going to happen when we're faced with such numbers of patients coming in with coronavirus.
"We're probably up to around 50 per cent of the consultant workforce at the Gwent in A&E who have swabbed positive for the coronavirus and a similar percent in our nursing team.
"It is proving a challenge when it's coming to staffing the department when we are facing these numbers coming through."
He also urged members of the public to stay indoors over the Easter weekend will impact the hospital's intensive care unit's capacity "in two weeks time" - as well as on staff "that are being put at risk and are being exposed to coronavirus".
Dr Rogerson said he has been off work since last Sunday (April 5) with a fever, aches, sore throat and a lack of a sense of smell.
He said: “I think, talking to other colleague I have had a mild to moderate set of symptoms.
“I know some of my colleagues in A&E have been quite sick and been off for a couple of weeks.
“So, I think that is probably a blessing to get started with, but I am obviously frustrated not to be in work.”
On Saturday health officials said a further 36 people have died after testing positive for coronavirus in Wales, bringing the total number of deaths to 351.
That news came as tributes have been paid to nurse Gareth Roberts after he died following a positive test for Covid-19.
On Sunday, it was confirmed that Donna Campbell, a cancer support nurse with Velindre had also died following a positive test for the virus,