Northern Ireland’s chief medical officer has urged all people who have been vaccinated against coronavirus to continue following public health measures.

Dr Michael McBride said those who have been inoculated, while protected themselves, may still be able to pass the virus on to others.

The warning came as Northern Ireland passed the landmark of 250,000 jabs administered.

On Tuesday, 258,311 jabs had been given, with 233,429 first doses and 24,882 second doses.

However Dr McBride said difficult months still lie ahead.

“It will be some many weeks before we see the vaccine doing the heavy lifting in terms of reducing the number of people requiring hospital care, because it is only when we get into those groups, over-50s, over-60s, who we are seeing in our hospitals at this time that we will begin to see that impact,” he said.

“We really do need to stick with this, we need to continue to follow all of the public health advice, abide by the restrictions. We have a long way to go.

“There is absolutely hope, the vaccines and the new treatments that are coming online are that hope, but there are many difficult weeks and months ahead.”

He said there is increasing evidence of the spread of new variants in Northern Ireland, with the more infectious Kent strain now thought to account for 50-60% of cases in the region.

A further 17 people have died with Covid-19 and there were another 447 positive cases, according to the Department of Health on Tuesday.

There were 716 Covid-positive inpatients in hospital, 66 in intensive care.

Dr McBride said the number of new cases is falling, and the number of new Covid-positive admissions to hospital has peaked and is starting to fall.

However he said serious pressures remain on respiratory wards and intensive care units.

He also warned that with the Kent variant of the virus more prevalent in Northern Ireland, the potential for exponential growth in the spread of the virus is significant.

Dr McBride also expressed concern at numbers of infections in the Armagh City, Banbridge and Craigavon and Mid Ulster council areas, adding there has been sustained prevalence.

He said the rate is falling, but not fast enough in those areas

“Despite looking at all the data, we have no clear explanation why that’s occurring at this time, although we will continue to examine the data, and if there is opportunities to intervene or indeed if there are further interventions we need to consider in those areas, then we won’t hesitate to advise of that action to ministers or local councils,” he said.

Patricia Donnelly, head of the vaccination programme in Northern Ireland, said the region had passed the landmark quarter of a million number, ahead of where officials had hoped to be at this stage.

She said they are expecting to receive further supplies of vaccine next week.

Asked about the newer vaccines, she said she expects to receive a consignment of the Moderna jab in April.

Novavax has not yet been approved, but Ms Donnelly said she would expect to receive it too.

“Our main programme has been running with the two principal vaccines (Pfizer and AstraZeneca) which have been very effective,” she said.

“If we get these others coming along, we will just open more centres, we will use community pharmacy, we will look at other ways we can use the vaccine, but we don’t expect there to be very large amounts.”