The Department of Health has started stockpiling key drugs in Northern Ireland as part of a contingency plan to deal with a no-deal Brexit.
Ulster Unionist health spokesman Roy Beggs had a briefing from health officials after the Belfast Telegraph revealed the contents of a leaked secret report which suggested patients' lives could be at risk if the UK crashes out of Europe without a deal.
The list of "reasonable worst case" scenarios included shortages of vaccines and medication, including some cancer therapies; difficulties running the children's heart surgery service, and more than 1,000 NHS employees being unable to get to work or quitting their jobs.
Mr Beggs said Brexit will "inevitably have major implications for health and social care".
"A no-deal exit in particular could have a drastic effect on patient care as the availability of staff, medicines and vaccines could all be impacted if not adequately planned for and managed," he said.
"During the briefing I was reassured to learn that a degree of stockpiling of key drugs and medical devices has already occurred, as well as planning for other time-sensitive medicines in order to minimise risks to patients. Last week I revealed there were almost 7,500 vacancies across the local health and social care system. It is essential therefore that there are no barriers put in place to impede or deter existing staff who are an essential part of the local health and social care system."
Alliance health spokeswoman Paula Bradley MLA said she was also "reassured" by the briefing but still had concerns. This included the lack of an agreement with the Treasury to pay for extra medicines.
Ms Bradley added there was a lack of information on the Government's Brexit advice website on how to access reciprocal healthcare in other EU countries.
European health insurance cards, she said, will no longer be valid after a no-deal and this could increase the cost of health insurance. She also said there was no clarity on a healthcare agreement between the UK and Irish governments in the event of a no-deal.