The National Public Health Emergency Team (Nphet) has recommended pausing the reopening of indoor hospitality in Ireland.
The recommendation was made during a late night meeting on Monday with the Cabinet Covid Committee.
The Government is set to make a decision on Tuesday on the return of indoor drinking and dining from July 5.
But the recommendations received from Nphet on Monday night were said to be “pessimistic” amid growing concerns over the spread of the Delta variant.
It is understood Nphet warned that a high level of transmission could have a significant impact on the reopening of schools in September.
Nphet recommended pausing the reopening of indoor hospitality until government comes up with an “enforceable” system to prove people have been vaccinated.
However, Nphet also recommended that the numbers attending wedding celebrations indoors in July could increase from 25 to 50.
Meanwhile, the National Immunisation Advisory Committee (NIAC) has recommended that the AstraZeneca and Janssen (Johnson & Johnson) vaccines can be administered to 18 to 40-year-olds.
The committee has also recommended that the AstraZeneca vaccine dose gap be reduced to four weeks, to allow more people in their 60s to be vaccinated faster.
Earlier, Tanaiste Leo Varadkar said a decision will not be made until Tuesday on whether Covid-19 restrictions will be eased further on July 5 as planned.
Taoiseach Micheal Martin has brought forward the decision on whether to delay the next planned round of coronavirus relaxations, due to rising concerns over the Delta variant.
A final call on the return to indoor dining and drinking had initially been expected later in the week.
However, ministers have faced intensifying calls from bar and restaurant owners to urgently provide clarity.
They have made the point that they need to tell their staff whether or not they will be working on July 5.
Mr Varadkar said the hospitality industry had made a “very reasonable” request to bring the decision forward.
“They have to engage employees, people have to come off PUP, they have to order supplies. So they’ve asked us that we bring the decision forward so we’re going to do that,” he said.
“We will make a decision tomorrow.”