Ireland is at risk of a significant resurgence in coronavirus, and care must be taken to avoid the infection being brought by people from one county to another post-lockdown, the expert tracking the disease here has warned.
Prof Philip Nolan, of Maynooth University, also revealed that for every one person detected with the virus there is another unknown - or possibly more - with the infection but with no symptoms.
There is a chance we could see "small second waves".
The warning comes as another nine people died yesterday from the virus, bringing the death toll to 1,691.
A further nine new cases were also confirmed as 110 patients with the infection were being treated in hospital, including 35 in intensive care.
Prof Nolan, who appeared before the Special Committee on the Covid-19 Response yesterday, was asked his view on the possibility of a second wave by Fianna Fail health spokesman Stephen Donnelly.
Prof Nolan, who leads the team advising the Government on how the virus is spreading, said he would be careful using the phrase "second wave".
"We need to be very careful that we don't transfer it from one part of the country to another," he told Sinn Fein TD Matt Carthy.
He was asked why the rate of infection was high in Cavan and Monaghan.
If outbreaks and clusters are excluded, it could be due to the counties being near Dublin which has been worst hit by the virus and there is a chance of "seeding out", Prof Nolan said.
For now, the spread of the disease is declining nationally despite the gradual opening-up from lockdown.
However, planning needs to be under way now for the possibility, with contingency plans in place to deal with a "tough" scenario should it happen.
The term "second wave" gives the public the impression that an overwhelming recurrence of the disease will "wash over them".
However, Prof Nolan said the country could see "manageable outbreaks". The management of the second wave will be different from the first wave and less of a blanket approach, he added.
Asked about the reduction in capacity in areas like public transport, public services and hospitals, and how long these will endure, Prof Nolan said we will learn a lot in the coming months about what carries low and high risk.
Meanwhile, a spokesperson for Health Minister Simon Harris yesterday declined to comment on confirmation by the HSE that its chief executive Paul Reid had been working from his home in Co Leitrim and been making essential trips to Dublin city, where he has another house, since March.
A HSE spokeswoman said that when domestic restrictions were imposed by the Government "Mr Reid and his family were located in Leitrim" and the home has been "his principal residence" since.
He has not lived in his Dublin house since travel restrictions were applied, she added.
Chief medical officer Dr Tony Holohan said: "While today we report nine new cases and the situation continues to improve in both Ireland and across Europe, the WHO has noted that now is not the time to take the foot off the pedal and that countries need to continue to work hard."