The Chief Medical Officer has warned the spread of Covid-19 is "out of control" with the number of cases doubling in less than a week.
The R number has risen to between 1.5 and 1.8 - the highest since March.
Restaurants and pubs serving food will close at 3pm this afternoon as part of new restrictions - while hairdressers and barbers will also shut later.
But Professor Philip Nolan, chair of NPHET's modelling advisory group, doesn't think those measures will bring the virus back under control
The government has reminded businesses that a number of supports are available for outlets forced to shut their doors.
Retailers have accepted that January sales can not go on as normal, but say stock will need to be cleared before spring.
Retail Excellence Ireland say sales will not be promoted in the same way as previous years and they expect a lot of transactions to go online.