According to Dr Nigel Ruddell, medical director of the Northern Ireland Ambulance Service (NIAS), some patients have had to wait for up to six hours to be admitted for treatment.
Meanwhile, one hospital has been forced to divert ambulances to other emergency departments to relieve bottlenecks.
Dr Ruddell told Sky News: “We’re bringing these patients in as emergencies and ideally, we want them into hospital to start getting their definitive treatment as quickly as possible.
“If we’re waiting sometimes up to six hours or more outside a hospital emergency department, then clearly that treatment is being delayed.
“In terms of our staff, they are constantly worried about those other patients out in the community who are awaiting on an ambulance response and that response has been significantly delayed.”
Starting from the first week of November, most recent data shows that the case rate in Northern Ireland rose from 420 for every 100,000 people to just under 600 over the course of a fortnight. The figures represent an increase of 40 per cent.
In Wales, the infection rate is currently around 500 per 100,000 people. In both England and Scotland, the number is around 400.
It comes after fresh work-from-home guidance was issued in Northern Ireland. Ministers also urged people to limit their social contact and wear face-coverings in crowded or indoor settings.
Deputy first minister Michelle O’Neill said that the measures were the best chance of avoiding further restrictions in the weeks ahead.
It comes as first minister Paul Givan said the Northern Ireland executive was “very much united” in urging the public to play its part in slowing the spread of Covid-19.
Speaking to the media following an agreement to reinforcedCovid measures, Mr Givan said they had considered a number of papers from Health Minister Robin Swann.
He said: “We are all very much united in asking the public to play its part along with us as politicians, that we can take every effort to try and minimise the transmission rate of the coronavirus.
“So we appeal again to redouble our efforts when it comes to trying to minimise some of those contacts, whenever it comes to having good ventilation, where you are meeting indoors try to meet outdoors more often.
“And we are emphasising that need to work from home where you can and for employers to support that.
“We recognise that in some circumstances that isn’t possible and practically people do need to be in their workplace.”
He added: “There is hope that we can come through this period over the next number of weeks by making that collective effort and taking personal responsibility seriously.”