A coronavirus cluster has been confirmed at the Royal Victoria Hospital in Belfast.
One patient and five members of staff linked to a cardiology ward have contracted Covid-19.
The BBC reported the development yesterday and said that staff received the positive results over the past fortnight, with testing ongoing.
The Belfast health trust said one patient was self-isolating but no-one was currently off work.
The Royal is among several hospitals which have been hit by outbreaks, with a high-level independent investigation ordered into cases at Craigavon Area Hospital and Daisy Hill in Newry, where a total of 11 patients have died.
Altnagelvin in Derry and Antrim Area Hospital have also been affected, while 10 ambulance workers tested positive following a golf outing.
During a press briefing earlier this week, Chief Medical Officer Dr Michael McBride said due to rising community infection rates, further outbreaks across hospitals and other healthcare settings were expected.
He said the north was "relatively fortunate" during the first wave in terms of fewer outbreaks in hospitals and care homes.
"We saw tragic consequences in those outbreaks where we did see them, but in terms of our comparison with other parts of the UK we saw fewer such outbreaks," he said.
"We now see rates of community transmission in Northern Ireland that are in excess of the Republic and other parts of the UK... I anticipate that we will see increasing numbers of cases in both hospital environments and care home environments despite the best efforts of staff.
"This is a highly transmissible virus and despite the use of PPE the virus does, and will, get in. All we can do is protect at an early point in time when it does and prevent that from spreading."
Dr McBride also issued a letter to healthcare professionals last month in which he warned about the impact of "lapses" when socialising together.
He wrote: "It is extremely challenging to maintain our guard at all times and this may inadvertently result in lapses in maintaining the recommended precautions in social interactions and other settings across our health and care facilities.
"It is therefore particularly important that we all remain vigilant in areas such as changing rooms, staff rooms, dining rooms and as they engage in conversations or interact in corridors and other settings when they are not engaged in direct patient facing activities."
