More than half a million people have received a Covid-19 vaccine in Northern Ireland.
Those aged over 65 and the clinically vulnerable are among those being booked in for jabs.
Health minister Robin Swann said it was a landmark moment.
“As of yesterday evening we had administered more than 509,000 vaccines,” he said.
“There are countries many times larger in population terms than Northern Ireland that are nowhere administering half a million jabs.
“That’s a huge achievement and I again I want to thank all our vaccinators, our organisers and our volunteers across trusts and primary care for reaching this milestone.”
A total of 478,825 first doses and 31,345 second doses have now been administered.
The health system has opened vaccination bookings to all carers aged 18 and over in Northern Ireland.
Feedback from the carer organisations indicates that a significant number of their members have taken up the offer and have already had the vaccine or have booked in the coming days.
Mr Swann added: “I am pleased to report that the regional vaccination centres are heavily booked for the next few weeks.
“I can also announce today that further vaccination appointments are being made available in the centres.
“These slots will be for those who are in the 65-plus age group and those who received a shielding letter because they are clinically extremely vulnerable to Covid-19.
“I would strongly encourage people in these two groups to book their appointments as soon as possible and to do so online if possible, to ease the pressure on the very busy telephone booking system.”
In line with the latest medical advice, those with a learning disability will be called forward by GPs for vaccination, if they haven’t received it through the health trust.
From April, the SSE Arena will be opened as a mass vaccination centre for Northern Ireland’s adult population aged 60 and under who have not yet received a vaccine via a trust or their GP.
In the coming months every adult will be offered a vaccine.
The Department of Health said: “Please remember to only book a vaccine slot if you are eligible. Do not make multiple bookings, you will automatically be booked for your second dose when your first appointment is confirmed.”
Vaccination teams have now completed their first visit to every care home in Northern Ireland.
Mr Swann announced on Tuesday the first confirmed cases of the South African variant of Covid-19 in the region. He said three cases of the variant had been confirmed.