All GCSE, AS and A-level examinations in Northern Ireland have been cancelled due to the pandemic.
More than 50,000 young people could be affected, last year’s student figures showed.
Some GCSE exams were due to take place next week, with more planned for February, May and June.
Schools have been closed down as part of strict measures designed to stem a rising tide of coronavirus cases entering hospital.
Stormont Education Minister Peter Weir said: “This is a very sad day for education, a sad day for young people.”
Work is under way on alternative awarding arrangements, he added.
He said all mainstream schools will be asked to provide remote learning until the half-term break in the middle of February.
Another 1,985 people have tested positive, the Department of Health said on Wednesday.
Thirteen more deaths were recorded.
Health Minister Robin Swann said: “This is a time to hunker down and weather the crisis.”
Flouting new movement restrictions could carry a fine of up to £5,000 and police will have the power to direct people to return home.
Robert Wilson, regional officer of the Association of School and College Leaders (ASCL) Northern Ireland, said it is essential there is public confidence in the system which replaces school exams.
“In the middle of all of this are young people,” he said.
“They need grades which reflect their efforts fairly and consistently, and which enable them to progress to the next stage in their lives.”
Special schools are to remain open as usual, while vulnerable youngsters and the children of key workers will have access to schools for supervised learning.
Provision in lieu of free school meals will be made, while childcare will remain open.
Mr Weir told Stormont Assembly the decisions were “not taken lightly”.
“We must have regard to the prevailing public health situation, and the need to reduce overall community contacts,” he said.
“I will return schools to face-to-face learning as soon as the public health situation prevails.”
Schooling has dominated the debate over Northern Ireland’s tighter new lockdown measures.
January’s tests for pupils seeking to transfer from primary to grammars were cancelled on Tuesday but hours later a date was set in February.
Stormont’s powersharing partners, Sinn Fein and the DUP, are fundamentally split over the need for a transfer test at age 10 or 11.
Deputy First Minister Michelle O’Neill has publicly urged a private firm organising the test to drop the plan.
Justin McCamphill, an official at teachers’ union NASUWT, said: “The (education) minister’s responsibilities in relation to exams do not end at GCSE and A-level.
“The minister must intervene and end the uncertainty around the transfer test for this year.
“The minister cannot simply wash his hands of the issue on the basis that the tests are ‘run by a private organisation’.
“All schools using the test are publicly funded and very much lie within the remit of the minister.”
Stay-at-home advice is to be put into legislation from midnight on Thursday, with additional powers being given to the Police Service of Northern Ireland (PSNI) to enforce the measures.
Household mixing will be reduced to just one other household or social bubble.