A "significant" number of people in Northern Ireland could still be at risk of dying from Covid-19, an expert has warned.
Dr Connor Bamford, a virologist at Queen's University, Belfast was speaking after the Department of Health (DoH) published new data on the potential impact of the virus beginning to spread again.
It examined what might happen if the region was hit by a second, potentially more lethal, wave of the virus if the 'R' number - the rate at which a single infected person infects others - creeps marginally above one.
The Queen's academic said that while the current R number is "nicely under one", the report highlights "the need for cautious vigilance" as more lockdown restrictions are lifted.
"As always, care must be taken as we relieve lockdown as the virus is still in Northern Ireland, the Republic and the UK and can easily have local flare ups if adequate social distancing is not maintained," he said.
However, another expert, former World Health Organization (WHO) chief Professor Karol Sikora said it is "very likely" Northern Ireland can avoid a second wave. He estimated the rate of infection could be much higher than thought, with up to 30% already having had the virus.
First Minister Arlene Foster and Deputy First Minister Michelle O'Neill referred to Department of Health data at yesterday's Stormont briefing.
They said the Executive's "incremental" approach to lifting the lockdown is crucial in trying to avoid a second wave.
"I'm not prepared to play with people's lives," Ms O'Neill said.
She stressed that a balance has to be struck between rebooting our economy and the "number one priority" of saving lives.
Mrs Foster explained: "We are very much aware of the enormity of the decisions we are taking, and we will always keep the transmission under close scrutiny to make sure we know where it is in the community and how it's moving."
Dr Bamford meanwhile said that "most people remain susceptible" to Covid-19, referring to the Department of Health bulletin which estimates that 5% of people here have already had coronavirus, according to antibody testing.
"It is thought that those 5% of people will be immune to the effects of the virus for at least a period of time - although for how long we do not know," he explained.
Dr Bamford said this modelling fits in with other regions worldwide which shows that the "vast majority of people have not been infected, are not immune and can likely be infected in the near future".
"This is why the report suggests that any future waves (here) will be worse, as any future waves could infect more than 5% of the population. There is still a significant amount of people who could get sick and die in the future," he continued. "All of this underscores the need for cautious vigilance as we go forward with relief of lockdown.
"On the positive side it shows that lockdown was effective as we knew the virus would be able to infect over 80% of people and we only let it infect 5%."
However, Prof Sikora said it is "very likely" Northern Ireland will not be hit with a second wave based on data from other parts of post-lockdown Europe.
He said it was likely Covid-19 will "peter out" here, but stressed it is important for authorities here to make contingencies.
"The deliberate release of lockdown in Austria, Czech, Norway and Denmark including bars and restaurants from April 14 has resulted in no spike," he stated.
Describing the DoH modelling as the "worst case scenario", he estimated the percentage of the population here who have had Covid-19 at 20% to 30%. Prof Sikora believes other mechanisms within the body - such as 'T cells' which help protect from viruses - would not be detected in antibody testing.
"Many people use other immune mechanisms, including T cells, and never make an antibody response," he added. "Antibodies are one defence mechanism, T cells are another. Also there are non-specific T cells; in other words, if you've had SARS (severe acute respiratory syndrome) or MERS (Middle East respiratory syndrome) there may be cross-immunity. It was shown last week that about 16% of people (worldwide) have cross-immunity to the current virus from old SARS and MERS."