Chief Medical Officer Dr Tony Holahan has said older and more vulnerable people should not leave their homes unless absolutely essential.
The warning comes as record numbers of Covid-19 cases were confirmed yesterday. The Department of Health said there were 3,394 new cases of the virus and four more deaths.
The National Public Health Emergency Team has said case numbers could rise further, warning that up to 6,000 a day could be seen at the peak of the current wave.
Covid-19 case numbers have been artificially low in the past week, as the IT system used to notify confirmed cases, struggled to cope with huge numbers of positive test results.