The coronavirus assessment centre at Londonderry's Altnagelvin hospital has reopened after staff sickness forced its temporary closure.
The Covid-19 Centre opened on Wednesday of last week but was forced to close over the weekend after 40 nurses had to self isolate.
Dr Tom Black, from the BMA, said that level of absence was "too big a number" for the facility to be able to provide a service.
The centre reopened on Monday morning.
"It worked well for three days, then we ran into a problem," Dr Black told BBC Radio Foyle.
"It was a bigger problem than we had anticipated. We knew staff would be off ill and we would have to cover them, and we had a pool of nurses and GPs."
"We had 40 nurses ill and isolating and that was just too big a number to cope with."
The assessment centre operates at the out-of-hours Western Urgent Care building at Altnagelvin.
Cases are assessed by GPs and the most seriously-ill patients are then transferred to specialist wards.
The Western Health and Social Care Trust (WHSCT) has now prioritised the nurse staffing levels at the centre, giving it the same status as ICU and the Accident and Emergency Department, Dr Black said.
That move has increased the pool of available nurses, he said.
Covid-19 testing for staff will also now be introduced.
A WHSCT spokeswoman apologised for the interruption in services.
"It is our priority that when the centre is open that we are providing care to our patients in a safe, effective and timely manner," she said.