Covid-19 vaccination centres in Northern Ireland have been opened up to all adults.
In recent week the centres have been primarily focusing on the 18-39 age group, with those aged 40 and over being offered first dose appointments through community pharmacies.
From 9am today, anyone aged 18 and over can book an appointment at a vaccination centre.
These centres are using the Pfizer vaccine for first doses.
The latest expansion of the vaccine programme has been made possible due to a scheduled increase in the supplies of the Pfizer jabs.
Northern Ireland's vaccine stock will be further boosted next week when the Moderna jabs will be used there for the first time.
People who already have appointments booked with a GP or community pharmacy are urged to keep them.
Community pharmacies will continue to offer vaccination slots for those aged 40 plus.
However, the pharmacies will no longer be offering vaccinations to under 40s.
Health Minister Robin Swann said: "I have been contacted by people in the 40 plus age group who wanted to be able to book their vaccine jabs in a vaccination centre. They can now do so.
"The vaccination programme has already reached about 80% of 40-49-year-olds. I believe today's announcement will help push that figure up even higher.
"Some appointment slots are still available at the centres for this weekend and we are today opening a fresh batch of slots for next week.
"My advice to everyone who has not yet come forward is to get your jab as soon as you can. The emergence and spread of the Covid-19 Delta variant demonstrates that the virus remains a serious threat.
"Getting vaccinated protects you and protects others. Vaccination is also essential to our pathway back to normality."
The vaccination centres are located at the SSE Arena and Royal Victoria Hospital in Belfast; the Foyle Arena in Derry; Omagh Leisure Centre; Enniskillen's Lakeland Forum; the South Lake Leisure Centre in Craigavon; and the Seven Towers Leisure Centre in Ballymena.
Chief Medical Officer Michael McBride stressed the importance of vaccination to the younger generations.
"Young people have had a particularly tough time during the pandemic and have made immense sacrifices," he said.
"They should see vaccination as a passport to a better life. They might think that their age protects them from the virus but that will not be the case for some of them. Also, when they get the vaccine, they are helping to protect their parents and grandparents and other older people they care about.
"This is the case even if those parents and grandparents have themselves been vaccinated. No vaccine ever provides 100% protection to 100% of people, but the more people we get covered, the harder it becomes for the virus to spread and do damage."
A number of localised initiatives are planned to help encourage take-up in June and July. These will include mobile, evening and walk-in clinics at different locations.
Patricia Donnelly, head of Northern Ireland's vaccination programme, said: "While walk-in clinics will suit some people better, I would still encourage as many people as possible to book.
"Booking helps us on the planning front, but also offers people a fast track in and out of the vaccination centres, at a specific time of their choosing.
"We are looking at all options that will help as many people as possible get both doses by the end of the summer."
198 new Covid cases in NI
The Department of Health has been notified of 198 additional cases of Covid-19 in Northern Ireland in the past 24 hours.
No further deaths related to the virus have been reported.
As of this morning, there were 18 patients with Covid-19 in hospital, none of whom were in intensive care.
