Schools in Northern Ireland will close from Monday until further notice.
First Minister Arlene Foster confirmed the move this evening, with Boris Johnson also confirming that all schools in England will also close.
Mr Johnson says that it means GCSE and A-level exams wouldn't take place in the summer, but work was underway to ensure students still receive their qualifications.
The announcements came nearly a week after the move to close schools in the Republic, and on the same day the Scottish and Welsh government announced their own measures.
Speaking to The Hard Shoulder this evening, Sinn Féin leader Mary Lou McDonald welcomed the move to close schools in the North - and called for an all-island approach to limiting the spread of the virus.
She said: "Michelle O’Neill has been pushing this issue, and no more than here in Dublin there are of course huge concerns in Belfast, Derry and the whole border region in terms of public health.
“We are in this together - all of us who live on this island, irrespective of our political outlook or view. Now is the time for all of us to pull together.”
She said an all-island approach was taken during the foot-and-mouth disease crisis, and that a similar effort is needed now.
Deputy McDonald said: "When it comes to animal health but even more when it’s a question of human health and public health, the population of the island is really a single population.
“The fact that we have two jurisdictions on the island is of course a political reality - but viruses don’t respect borders.
"We need to bring the North up to speed with the South in certain things, and then together as a single island we need to advance and do every single thing that we can."
The Sinn Féin leader was also asked about the prospect of a temporary national government to deal with the crisis.
The Green Party has led the calls to set up such a temporary government, saying full government negotiations should be suspended for now.
Deputy McDonald said: “I think we need to look at every option.
"I think [a national government] could be difficult to put together, I think it could be cumbersome, but we will consider every proposal that’s on the table."
