The Taoiseach says pubs and restaurants in the three counties will have to close, as part of the local lockdown.
Micheál Martin says people shouldn't use public transport unless it's absolutely essential.
He says the restrictions are needed because the virus is a 'deep and urgent threat'.
The rest of the country will remain in Phase 3.
The decisions being made after the Taoiseach received new advice from the National Public Health Emergency Team on rising cases in the midlands.
The three counties have seen 226 cases in the past 2 weeks, mainly in meat plants.
Those cases accounted for half of all cases in the country in the last fortnight.
- restaurants / pubs close except for takeaway
- nursing home visits and visits to prisons suspended
- preparations for school reopening continue
- Householders to Restrict visitors to 6 people from no more than 3 homes
- Non contact sport groups of no more than 15
- Contact sports cease