The Taoiseach says there may be "stricter social distancing measures" in the future if the Coronavirus reappears.
"The easing of public health measures will require continuous effort by all of us to suppress some control of this virus," he said.
"We will not necessarily mirror the manner in which they were escalated.
"We must leave a period of time between taking each step. So we can monitor their impact on society.
"Certain stricter social distancing measures may have to be reintroduced, if it looks like the virus is increasing again.
"We've seen this happen unfortunately in Japan in recent days.
"Today, our new enemy is complacency.
"The risk is that if we become lax in the next few days or weeks, we could lose control over the spread of the virus."
Restrictions on movement are due to run out on May 5, amid growing public pressure to ease the guidelines in certain areas in order to protect the Irish economy.
Speaking on the Dáil on Thursday, Leo Varadkar was also quizzed by a number of TDs on testing capacity, which Ireland has still not met from it's early targets, said criteria could change again in a few days, after a decision is made by the National Public Health Emergency Team (NPHET).
Ireland adopted the World Health Organization (WHO) case definition for Covid-19 on March 25, which means only patients presenting with fever and at least one sign of respiratory illness such as a cough will be tested.
The change was criticised at the time, as many believe ramping up testing will be key in Ireland's fight against COVID19.
"This is a rapidly changing system," Mr Varadkar said.
"Facts change by the day, things we thought were true a few days ago, are not true today.
"In terms of questions on testing, I am told by the HSE that we can ramp up to 10,000 per day in testing centres, with a referral appointment time of 24 hours."
Hospitals are currently doing 1,500 tests per day, the ambulance service are doing 1,500 tests a day.
"The criteria for testing has changed, and will change, but I need to be frank, when you widen criteria, there will be excess demand," Mr Varadkar added.
"We may find ourselves overwhelmed and backlogged all over again, it's just you can only guess how these changes will affect demand.
"Up until 3 weeks ago, we were told it wasn't useful to test asymptomatic patients, the science was that that kind of testing wasn't valuable, that's now changed.
"It now appears that you can pick up COVID19 in asymptomatic patients"
TDs had the chance to put questions to Leo Varadkar in the Dáil from 12 noon, only one TD, Clare's Independent representative Michael McNamara, left time for Mr Varadkar to reply to their queries, at 13:50pm, ten minutes before the Taoiseach had to leave for the European Council teleconference.
The Taoiseach said the Dáil Business Committee should think about how better to do such question sessions, as he had six pages of questions written down that he had no time to answer.