People in Northern Ireland have been urged not to drop their guard after the coronavirus alert level was reduced.
The UK's chief medical officers agreed to downgrade the level from four to three after a "steady" and continuing decrease in cases in all four nations.
Localised outbreaks of Covid-19 are still "likely" to occur, the advisers warned, and the virus remains in general circulation.
But the downgrading - recommended by the Joint Biosecurity Centre (JBC) - means transmission of coronavirus is no longer considered to be "high or rising exponentially".
Health Secretary Matt Hancock said moving to a lower alert level is a "big moment" for the UK, and showed the country is getting "back on her feet".
England's Professor Chris Whitty, Northern Ireland's Dr Michael McBride, Scotland's Dr Gregor Smith and Wales' Dr Chris Jones agreed with the JBC's recommendation.
They said: "The Joint Biosecurity Centre has recommended that the Covid-19 alert level should move from level four (a Covid-19 epidemic is in general circulation; transmission is high or rising exponentially) to level three (a Covid-19 epidemic is in general circulation). The CMOs for England, Scotland, Wales and Northern Ireland have reviewed the evidence and agree with this recommendation to move to level three across the UK.
"There has been a steady decrease in cases we have seen in all four nations, and this continues."
However, Dr McBride said now is not the time for people in Northern Ireland to be complacent.
He said: "Now is not the time to drop our guard.
"The decision to reduce the alert level is an acknowledgement that we have moved from a situation where there was a high and rising level of transmission of the virus, but it is vital that we remain aware that the virus continues to circulate in Northern Ireland.
"It still poses a real and continuing threat, particularly to the older and the most vulnerable members of our society," he added.
Mr Hancock said: "The UK moving to a lower alert level is a big moment for the country, and a real testament to the British people's determination to beat this virus."
But former chief scientific adviser to the Government Sir David King said that lowering the alert level was "a very strange decision to make at this point in time".