Speaking on RTÉ's Brendan O'Connor programme, Dr Cillian De Gascun said that the next two weeks were a "critical phase" during which it is hoped that current restrictions will start to result in a drop in the Covid-19 infection rate.
However, Dr De Gascun said they would not exclude any measures and that the only priority for NPHET was public health.
"So we have to be very careful about that," he said. "We don't want to go back into a national lockdown if we don't have to.
"But I think the key thing to remember about the stay-at-home restrictions is that they did work. That's why it is there, it's a tool in the armoury that you never exclude definitively."
This is a change that has to stay with us.
He said that it was vital for people to follow updated Government advice, as the affects of a second national lockdown would strain the already tested economy.
Dr De Gascun added: "Although we're reopening society and getting back to the activities that we used to do, we have to do them in a different way.
"There's nothing that is zero-risk unfortunately so we want people to get to school and have dinner with friends and have friends over to their house, but the thing is when they do those things we have to do them differently now.
"It's really like a change in behaviour. An analogy we might use is the way we changed from plastic bags to bags for life. This is a change that has to stay with us."
There were 142 additional Covid-19 cases confirmed in the Republic of Ireland today while no further coronavirus related deaths were reported.
There has been a total of 1,777 Covid-19 related deaths in Ireland. There is now a total of 28,720 confirmed cases of Covid-19 in Ireland.
Of the cases confirmed on Saturday:
- 74 are men / 66 are women
- 69 per cent are under 45 years of age
- 32 are confirmed to be associated with outbreaks or are close contacts of a confirmed case
- 19 cases have been identified as community transmission
- 59 are in Dublin, 20 in Kildare, 14 in Donegal, 14 in Limerick, eight in Wexford, six in Tipperary and the remaining 21 are located in Carlow, Clare, Cork, Kerry, Kilkenny, Laois, Louth, Mayo, Meath and Wicklow
Acting chief medical officer Dr Ronan Glynn said: “Today marks six months since our first case of Covid-19. It has been a very difficult time for many and few have been left untouched in some way by the negative effects of this pandemic.
“However, it has also been a time of incredible solidarity, a time when a sense of community has come to the fore. We have seen innovation, cooperation, volunteerism and charity, and kindness on an enormous scale. Our frontline workers have stepped up again and again. But underpinning it all has been each person playing their part by making the right choices, many times, each day. Together, we have broken the chains of transmission and flattened the curve. As cases rise again, it is these same behaviours that will once again make the difference, protecting ourselves, our families and our communities."
