Some people aged 35 to 39 will now be able to access a Covid-19 vaccine in Northern Ireland.
The Department of Health announced "limited availability" for that age cohort ahead of the vaccine programme being fully opened to them at the end of April.
People can book from 2pm, with appointments mainly available at the mass vaccine centre at the SSE Arena in Belfast.
The department said appointments in community pharmacies will be made available to 35-39-year-olds later in April as vaccine supplies permit.
Health Minister Robin Swann said: "I have always been clear that we would move through the vaccine programme as quickly as vaccine deliveries and capacity allows, as recommended by JCVI.
"I recently announced that we successfully administered over one million vaccines across Northern Ireland to the highest priority groups. This figure is expected to rise exponentially as the trust vaccine centres and GP practices continue to deliver second doses while the vaccine centre at the SSE Arena and the Community pharmacists push ahead to deliver first doses.
"Opening up to 35-39-year-olds earlier than expected is a testament to the hard work and dedication of all staff who are delivering the vaccination programme in Northern Ireland.
"I encourage those who are eligible to seize this opportunity and take up the offer of vaccination. Getting the vaccine not only protects you but also those close to you.
"I would also strongly encourage anyone aged 40 years or over who hasn't booked themselves a vaccination appointment yet to do so as soon as possible," he added.
There were no further deaths of patients who previously tested positive for Covid-19 announced in Northern Ireland.
However, another 79 people had tested positive for the virus, while there were 69 confirmed Covid-19 inpatients in hospital, eight of whom were in ICU.