© Professor Ian Young. Chief medical officer Dr Michael McBride had warned that any extension to the circuit breaker of less than two full weeks would cause excess deaths.
Professor Ian Young said there was a desire and will across the UK and Ireland to allow families to celebrate this festive season, but warned relaxing restrictions risked driving up infection.
Professor Young added: "We anticipate an increased transmission of the virus and in due course an increase in terms of pressure on hospitals in relation to admissions and inpatients.
"The modelling suggests it is more likely than not that additional intervention of some kind would be required before Christmas in order to avoid pressures on the hospital system becoming overwhelming."
The R rate is about one at the minute.
Medical chiefs believe the extra restrictions imposed in places like Londonderry and Strabane have worked as predicted in driving down the rate of infection.
Professor Young said sectors contributing to interactions included close contact services, hospitality and education.
"There are no easy solutions and there are no new solutions," he added.
Stormont's leaders have clashed over a contentious voting mechanism that enabled the DUP to throw out the proposed extension of Northern Ireland's circuit-break backed by doctors.
Professor Young added he was "optimistic and positive" about the potential impact of vaccination and also the potential increase in testing.
He said: "They have huge potential to change things."
He said it would be next year before much of that began to make an impact.
A number of successful vaccination trial results have been announced over recent days.
Professor Young said he looked forward to discussing with the hospitality sector what additional measures it can put in place to limit that risk as much as possible when it reopens.
"There are some additional mitigations that might be useful," he said.
"Paying more attention to ventilation and possibility of limiting the numbers who can be present in various premises."
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