Video report by ITV Wales Health Correspondent James Crichton-Smith
Eight people have died at the Royal Glamorgan Hospital after 82 cases of coronavirus were identified there.
Temporary restrictions to services have now been put in place at Royal Glamorgan Hospital in Llantrisant, including suspending planned surgery, with the exception of a small number of urgent cancer cases.
Cwm Taf Morgannwg University Health Board says ambulances will be diverted to Bridgend, Merthyr, and Cardiff.
It says there are currently 82 Covid-19 cases at the hospital near Llantrisant, including six in intensive care.
The health board says it is taking on a number of "urgent and significant" actions to try to contain the virus and ensure the safety of its staff and patients.
The following restrictions are now in place at the hospital:
Temporary suspension of planned surgery at the hospital (with the exception of a very small number of urgent cancer cases which have been clinically prioritised)
Any adult patient requiring an emergency admission following assessment, who would normally be admitted to the Royal Glamorgan Hospital, will be taken to either Princess of Wales Hospital in Bridgend, Prince Charles Hospital in Merthyr Tydfil, or the University Hospital of Wales in Cardiff
The Emergency Department at the Royal Glamorgan Hospital will remain open for walk-in patients and those who can be treated in ambulatory care department (an area in the Emergency Department at the Royal Glamorgan Hospital)
Ambulances will be diverted temporarily to alternative sites, namely Princess of Wales Hospital Bridgend, Prince Charles Hospital Merthyr Tydfil and University Hospital of Wales Cardiff
Cwm Taf Morgannwg University Health Board says the paediatric wards at Royal Glamorgan Hospital will remain open, however it is looking into whether plans for The Tirion Birthing Centre, which has been temporarily closed during the pandemic, can be reopened.
It is also working closely with Public Health Wales to increase the number of tests for both patients and staff at the hospital and says it is reviewing the situation on a daily basis.
On Wednesday, Welsh education minister Kirsty Williams said the Welsh Government was working with the health board and Public Health Wales to address the "issues" which have given rise to the outbreak.
She told the Welsh Government Covid-19 press briefing: "We understand that this is a serious situation and how upsetting it is for all those involved.
"We are working with the local health authority's senior management team and Public Health Wales to understand and, crucially, address the issues that have arisen at the Royal Glamorgan Hospital to bring that outbreak under control and learn the lessons of that so they can be applied in other healthcare settings."
She added: "The situation is a worrying one, and all steps are being taken to protect existing patients, staff, and to ensure that those residents that were due to leave the hospital are directed to appropriate care in other hospitals in the near vicinity."
Paul Mears, CEO of Cwm Taf Morgannwg University Health Board, said: “We recognise the concern that these temporary changes will cause and would like to assure our patients and communities that managing this outbreak is our key priority.
“These decisions have not been taken lightly, and we understand that they will impact our patients, their families, our staff and partner organisations. However, the safety of our patients and staff is of the utmost importance and we believe this is the right course of action, based on the professional advice given to us.
“It’s important to state that Royal Glamorgan Hospital is still open for patients requiring emergency department services, although we would encourage everyone at this time to consider where alternative services can provide the care suitable for their needs such as the NHS 111 Wales website, minor injury units and GP services.
“We will provide further advice and guidance within the next 24 hours and will continue to communicate widely with our communities, patients, stakeholders and colleagues to ensure everyone is aware of the temporary changes and what this means for accessing services at Royal Glamorgan Hospital."