Health authorities have said there is no evidence that Covid-19 was spreading in Northern Ireland in the months before the first confirmed case.
It follows reports from people who said they or their relatives had symptoms similar to the virus as far back as December.
In an interview with the Belfast Telegraph yesterday, former SDLP councillor Declan Boyle said he believed members of his family could have had the virus before Christmas.
Covid-19 was not confirmed here until late February.
Following Mr Boyle's interview, others came forward to say they believed they may have had the virus in December.
Similar reports have emerged across the UK and beyond.
Taoiseach Leo Varadkar has previously said it was "very possible" that coronavirus reached Ireland in December.
However, the Public Health Agency said there was no evidence to indicate the virus was present before February.
Mr Boyle fell ill in March. He said the symptoms he displayed - exhaustion and loss of appetite - were identical to those experienced by his wife and one of his sons in December.
Since then this newspaper has become aware of other members of the public who believe they had Covid-19 before Christmas.
One individual visited their GP twice after taking ill, experiencing a severe cough, a raised temperature and a loss of weight.
The man explained he was subsequently prescribed two courses of antibiotics and it took about six weeks to fully recover. He said he was aware of other people in his area - and further afield - who had similar symptoms.
Dr Connor Bamford, a virologist at Queen's University, cautioned against speculation over earlier cases.
He said that without careful scientific and medical testing of these cases, there is no way of definitively knowing if the virus was present here last winter.
"It's near impossible to say for sure and it is fairly unlikely," he said. "Based on symptoms lots of things will look like Covid, like a bad flu for example.
"Even if there were some cryptic 2019 Covid cases, we do know that the NI Sars-CoV-2 outbreak began in earnest in late February/early March and not in December 2019."
The Public Health Agency said: "There is no evidence to suggest Covid-19 was circulating in the community in December."
Do you suspect you had coronavirus before February? Contact firstname.lastname@example.org