Nurses at one hospital have been "emotionally attacked" and "victimised" by members of the public - according to a senior doctor.
Nerys Conway, a consultant at the Royal Glamorgan Hospital in Llantrisant said there were "awful cases" of abuse.
The hospital has been the centre of a large recent outbreak of Covid-19.
So far 186 cases and 51 deaths have been linked to a Covid-19 outbreak at the hospital, although infection rates appear to have stabilised more recently.
Dr Conway said the experience has been "horrendous" for staff working hard to care for patients during the latest wave of the coronavirus, who have received abuse both in person and on social media about infection rates within the hospital.
"I know of some awful cases where nurses have been emotionally attacked outside of work - there has been some name-calling, people have been victimised - that has been horrendous."
"Some of the nurses have experienced awful emotional abuse on social media or while out walking.
"I feel incredibly sorry for them in particular because I have witnessed the most dedicated team of nurses throughout all of the wards here, I am incredibly proud of them - they have looked after people and their families so well."
Along with infections at the Royal Glamorgan Hospital, there have also been significant outbreaks at the Cwm Taf Morgannwg health board's other two large hospitals.
The Princess of Wales Hospital in Bridgend has recorded 180 cases and 40 deaths so far, while there have been 90 cases and 20 deaths linked to an outbreak at the Prince Charles Hospital in Merthyr Tydfil.
He said abuse in person, over the phone or online was "totally unacceptable" and would not be tolerated.
"We are immensely proud of our workforce and their well-being is paramount as we head into what will inevitably be a difficult winter.
"We are calling on everyone across our communities to support our staff and recognise the incredible work they are doing at this challenging time."
Dr David Bailey, chairman of the Welsh Council of the British Medical Association said some patients were lashing out in frustration which was "clearly not helping anyone".
He added: "There's an awful lot of long-term problems that are building up at the moment and I think people are just becoming frustrated, they're becoming impatient when they hear the news that there is something [Covid-related] coming up.
"They're becoming impatient to start to return to something like their normal lives."
Updated figures for infections at hospitals within the Cwm Taf Morgannwg health board area are due to be published on Tuesday.
Health board bosses say staff have worked hard to tighten up infection control procedures, but insist it is very difficult to prevent hospital infections when Covid is spreading widely in local communities.
Last week the chief executive of NHS Wales reiterated that view while insisting the numbers of people catching Covid in hospital only accounted for a small percentage of total infections.
Andrew Goodall said: "I want to be clear, this is not as simple as a failure of hand-washing or poor infection control procedures,"
"This virus is highly infectious and it can be passed on in the asymptomatic, pre-symptomatic and symptomatic phases of the infection.
"It is incredibly difficult to prevent its spread in busy healthcare environments, especially with around 90 people with Covid currently admitted each day," he told journalists last Tuesday.