The Director of the National Virus Reference Laboratory says the UK variant of COVID-19 will become the dominant variant in Ireland.
Dr Cillian De Gascun warned it has adapted and is better at moving from person to person.
He said we must "reduce its opportunities to spread" by cutting out socialising, staying home, not visiting other houses or attending illegal gatherings.
It comes as 60 further deaths and 3,231 new cases of coronavirus were confirmed in the Republic yesterday.
Dublin GP Dr Ray Walley said that while the numbers are coming down, we still have a long way to go.
"We are far from there [yet], we're still the country in Europe that has the worst figures," he told Newstalk Breakfast with Susan Keogh.
"When we say things are improving, they're improving from an astronomical high.
"The mood music behind the scenes is, unfortunately, our hospitals and surge capacity."
Dr Walley added that while people's close contacts have gone down from six to 2.3 since December, "that's still too high".
"The unfortunate thing is we're still in very difficult times with a projection of 600 to 1,000 deaths in January and people need to listen to that," he said.
"We need to consider that we all have COVID-19, to stay away from each other, to ensure we're not going to infect people."
He confirmed that 1,900 GPs and practice nurses were vaccinated against COVID-19 yesterday which was 100 more than expected.
They received the Moderna dose at three new mass vaccination centres in Dublin, Galway and Portlaoise, with teams inoculating healthcare workers until 9pm last night.
Good news as ofJAN 15 but better again after 1900 GPs/Practice Nurses vaccinated on 17/1/21 who will become the vaccinators of many in the future #vaccinessavelives #covid19 pic.twitter.com/B81JORyhPr
— Ray Walley (@WalleyRay) January 17, 2021
Dr Walley said it was "great news" that Ireland has a bid in to get supplies of the AstraZeneca vaccine.
"That is a game-changer in general practice in Northern Ireland and the UK and it will be a game-changer here as well," he said.
Ireland has done "incredibly well" in handling the pandemic, with data this week showing we had the highest daily vaccination levels in the EU.
"Denmark was a country we were behind the other day and now we're ahead and it's going to be a bit neck and neck," Dr Walley explained.
"But with everything we've done, even with testing, we've actually been up there in the top three and four.
"Nobody talks about the testing regimen anymore, they take it for granted, nobody's talking about the fact you get the results very quickly, they take it for granted.
In terms of the country's inoculation programme, Dr Walley stated a lot will depend on vaccine supply but "effectively we are getting there".
He said the second dose for people who have already received their first dose of the vaccine has been put away so supply will be guaranteed for 28 days' time.
