A hospital has reinstated a temporary ban on visits to patients, except those receiving end-of-life-care, due to a rise in Covid cases.
People are also asked to attend outpatient appointments alone at Withybush Hospital in Haverfordwest, Pembrokeshire.
Masks are also now required for all on-site visits.
Hywel Dda University Health Board, covering west and mid Wales, is the third Welsh board to bring back masks.
Two of the seven boards, Aneurin Bevan and Cwm Taf Morgannwg, both in south Wales, asked people to wear masks at their hospitals last month.
On Monday evening, Aneurin Bevan also issued a plea for people to stay away from its hospitals unless “absolutely necessary” due to “extreme pressure”.
Aneurin Bevan did not mention Covid as a reason for its appeal.
The board, which covers Blaenau Gwent, Caerphilly, Monmouthshire, Newport, Torfaen and south Powys, said the emergency department at The Grange University Hospital in Cwmbran “remains very busy”.
Aneurin Bevan asked people to attend only if they have “a life-threatening illness or serious injury”. Anyone with a less serious issue is asked to visit a minor injury unit in Newport, Abergavenny, Ystrad Mynach, or Ebbw Vale.
Hywel Dda encouraged staff and contractors to have a lateral flow test, and report the result, twice a week.
“We have made the decision to reinforce these measures at Withybush Hospital to reduce the risk to our patients and staff,” said Mandy Rayani, director of nursing, quality and patient experience.
“We can all continue to take protective measures to reduce the risk of transmission of Covid-19 to protect vulnerable people and the NHS.
A designated partner can attend antenatal appointments or scans at Withybush Hospital midwifery-led unit and any visits considered necessary through agreement with a ward sister or charge nurse.