Elective surgeries have been cancelled at University Hospital Waterford and Kilcreene Orthopaedic Hospital today (Thursday).
The HSE issued the update on UHW and Kilcreene today, advising people to expect delays and to only attend the Emergency Department if it is urgent.
It comes as hospitals deal with a backlog in testing, following yesterday's strike of medical scientists.
The Union representing Medical Scientists – the Medical Laboratory Scientists Association (MLSA) says the scientists working in hospital laboratories are facing significant levels of burnout because of a severe recruitment and retention problem.
The industrial action follows many rounds of unsuccessful talks with HSE and Department of Health, and it is expected further strikes will take place in the coming weeks