Northern Ireland's mass vaccination centre has been hailed as a "significant milestone" in the fight against coronavirus.
The SSE Arena in Belfast will have the capacity to administer jabs to 40,000 people a week.
A slowdown in the UK's vaccine supply lines will see the centre processing around 11,000 people a week initially, with the numbers ramping up as more AstraZeneca jabs become available.
The SSE will operate as a mass vaccination site for the whole of Northern Ireland.
Several regional centres will continue to administer vaccines, as will GP surgeries.
Visiting the arena floor, which has the capacity for 60 separate vaccination stations, First Minister Arlene Foster said its opening is a "significant milestone" in the roll out of the vaccination programme.
"Our vaccination centres are ramping up, I am delighted to be here to see the professionalism of our staff yet again," she said.
"It's been a really good week to mark more milestones, 30 million people across the United Kingdom have now received their first dose of their vaccine and in Northern Ireland over 50% of adults have received their vaccines."
Mrs Foster added that she was "perfectly well" after her vaccine on Saturday apart from a sore arm on Sunday.
Executive ministers are set to meet on Thursday to discuss the latest state of restrictions.
Mrs Foster said numbers are "going in the right direction in Northern Ireland" with incident rates down to "around 53 in 100,000".
She said young people have been prioritised in the move out of lockdown with all to be back in school by April 12.
"We will be looking at the outdoor activities again, our pathway is very clear on those things that we will be moving through now, and our taskforce will be bringing us recommendations as to how we can move forward," she said.
Deputy First Minister Michelle O'Neill said it was a day for hope and optimism.
"To walk through the SSE Arena would lift everybody's heart," she said.
"People have all stepped up to deliver what is a very ambitious vaccination programme, and all credit is due to all people who have made this happen.
"It really is a fantastic day."
Ahead of Thursday's Executive meeting Ms O'Neill said: "We think April 15 gives us the next opportunity to be able to announce some more easements.
"It needs to be steady and it needs to be slow and gradual in order to allow us to move forwards and not backwards."
Health Minister Robin Swann described the SSE as a vaccination centre as "an amazing sight".
"This is a great day for Northern Ireland when we're seeing this level of vaccination," he said.
This week more than 300 community pharmacies will also become involved in the vaccine roll-out.
Mr Swann added: "Not only are we looking at a greater regional approach, we'll also be looking at a greater local approach to get any many people vaccinated as quickly and as efficiently as possible."
The minister said Northern Ireland had already made "huge inroads" in delivering the vaccine to over half of the adult population.
"The opening of this centre will enable the programme to expand at an even quicker rate and I hope to announce very soon that I will be opening the programme to additional age cohorts to allow more of those eligible to book their vaccination," Mr Swann said.
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The SSE Arena is the home of the Belfast Giants ice hockey team, and prior to the pandemic was the region's main venue for indoor concerts.
Its opening as a mass vaccination centre was originally expected to be accompanied by an expansion of the vaccine programme to take in the 40-49 age cohort.
That move has been delayed by a number of weeks due to the recent issues with the delivery of UK-wide orders of AstraZeneca jabs from overseas.
AstraZeneca and Pfizer jabs are currently being administered in Northern Ireland, with Moderna doses expected to be added to the rollout in the coming weeks.
As of Sunday, 850,041 vaccines had been administered in Northern Ireland, 726,589 of which were first doses and 123,452 were second doses.
The region is on course to offer first jabs to the entire adult population, 1.4 million, by July.
Gary Davidson from Lisbane in Co Down was the first to get a vaccine in the SSE Arena this morning.
The 55-year-old was last at the venue with his sons to watch a motocross event.
"I feel very proud to see what's going on in the SSE in Belfast," he said.
"I feel as if I am protected and hopefully won't be able to pass it on to relatives."
Mr Davidson added: "I didn't think I would ever be here for this, but I'm very impressed by what's going on in the Health Department."
No further deaths of people who previously tested positive for Covid-19 in Northern Ireland were reported by the Department of Health on Monday.
Another 65 confirmed cases of the virus were recorded in the last 24-hour reporting period.
This morning, there were 129 Covid-positive confirmed inpatients in hospital, of whom 17 were in ICUs.
