The ambulance service in Northern Ireland is braced for delays and hospitals have reached full capacity in Northern Ireland.
Overall bed occupancy is at 100%, with only six beds still empty, latest official figures show.
Paramedic chiefs have warned that Covid-19 staff sickness absences could delay answers to 999 calls at one of the busiest times of year.
Around 160 employees were off work for pandemic-related reasons.
Response times for less urgent cases were expected to be increased and emergency callers could wait longer on the line.
Meanwhile, schools will deliver remote learning in the first week of the new term after a return to classrooms was delayed due to spiralling Covid-19 infection rates.
A Northern Ireland Ambulance Service (NIAS) statement said: "Unfortunately, the NIAS Emergency Ambulance Control Room is currently experiencing absences due to Covid-19, and contingency planning to mitigate the potential risk to service disruption is ongoing.
"This has put our service under even more pressure and we anticipate that callers to 999 may, at times, experience a delay in having their calls answered."
A further 11 people have died with Covid-19, Stormont's Department of Health said.
Another 1,929 individuals had tested positive.
Hospital bed occupancy was running to 467, with 34 in an intensive care unit and 27 on a ventilator.
A total of 107 care home Covid-19 outbreaks were being addressed.
Education Minister Peter Weir said the delay in reopening schools would affect both primary and secondary settings.
For secondary school Years 8 to 11, remote learning would continue throughout January.
Schools would open next week to accommodate vulnerable children and those of key workers.
Childcare settings, including those attached to schools, pre-school facilities, nurseries and special schools, would also open as usual next week.
Mr Weir had been facing mounting pressure to delay the return to school after the Christmas holidays due to worsening infection rates.
The minister said exams due in January would take place compliant with public health advice.
He said schools would have flexibility to deliver face-to-face learning for pupils due to sit those exams if they wished.
"I must stress that these decisions are not made lightly as I know the negative impact on children's learning and mental health and wellbeing of not being in school," he said.
"However, particularly after unprecedented levels of positive Covid-19 tests since Christmas, and the pressure this applies to our health service, it is critical that we all must consider the public health and scientific advice as we look forward to brighter days ahead."
The roll-out of the Oxford/AstraZeneca vaccine in Northern Ireland will begin at GP practices on Monday.
An initial batch of 50,000 doses has been allocated and those aged over 80 will be initially prioritised.
Chief medical officer Dr Michael McBride said as many people on the priority list as possible should be offered a first dose.
He added: "The evidence shows that the initial dose of vaccine offers as much as 70% protection against the effects of the virus.
"Providing that level of protection on a large scale will have the greatest impact on reducing mortality and hospitalisations, protecting the health and social care system. It is the right thing to do for the public health."
Call for people not to mix this New Year's Eve
Frances O'Hagan, Deputy Chair of the British Medical Association's GP Committee in Northern Ireland, has said the situation in the North is shocking regarding the high number of people who are infected with Covid-19.
Speaking on RTÉ's Morning Ireland programme, she said the positive cases are rising and subsequently turning into hospital admissions.
She said GPs are extremely busy and called on people to be careful not to mix with others this New Year's Eve.
"If we have a huge house party we are at risk of making it so much worse. We need to be very careful tonight and over the next few days not to socialise."
She said the Oxford AstraZeneca vaccine will be available to GP practices from the beginning of next week.
"We are going to move heaven and earth to make sure we have the vaccine available and into the arms of our patients from early next week," Dr O'Hagan said.
She said it is really important in light of the high number of cases among elderly people.