The Irish Nurses and Midwives Organisation says overcrowding in hospitals could cause a risk of cross-infection from Covid-19.
It's very concerned by rising trolley numbers it's seen in emergency departments over the past week.
The union and Irish Association for Emergency Medicine warn that the "problems of the past" may re-emerge as non-Covid treatments are ramped up.
INMO general secretary is Naas woman, Phil Ni Sheaghdha.
She is calling on the government to keep using private hospitals for public patients: