Health officials have begun tracing hundreds of airline passengers who shared a flight from Italy with a woman who has tested positive for the coronavirus.
The woman, who is from the east of the country, is the second person to test positive for the virus in the Republic.
Her infection is not linked to the case of a Dublin school pupil who also picked up the virus while in northern Italy.
She is now believed to be in isolation in Dublin's Mater Hospital.
Chief Medical Officer Dr Tony Holohan said tracing of her contacts was under way.
The Department of Foreign Affairs updated its travel advice last night, urging people to avoid all non-essential travel to four regions in northern Italy - Lombardy, Veneto, Piedmont and Emilia-Romagna.
Meanwhile, major questions have emerged over the handling of the first person to have the coronavirus here after it was claimed he was at band practice in a community hall shortly before the positive test was announced.
Anyone suspected of having the virus should be in self-isolation until their test result gives the all-clear.
But the case of the school pupil who tested positive after a trip to Italy was thrown into confusion when a leaked HSE letter said he was at band practice between 6pm and 8pm on Saturday.
The Department of Health announced the first confirmed case shortly before 9pm.
Public health doctors, as per protocol, would advise the suspected case about the need to isolate themselves from others in their homes and observe strict guidelines on the sharing of any cutlery or bathroom facilities.
The issue came to light yesterday after a letter from the HSE to the parents of teenagers in a local band, of which the pupil is a member, was leaked. It stated the other band members needed to go into self-isolation.
The letter was written on Monday, although the pupil had been confirmed as having the virus on Saturday night, leading to a two-week closure of his school.
Adding to the confusion, the Department of Health described the letter as a hoax yesterday morning, leading to an on-air apology from RTÉ.
On its Twitter page the department said "we are aware of fake letter circulating regarding the confirmed case of Covid-19".
But after the letter was proven to be true, the tweet was deleted.
While the letter was later confirmed as genuine by the HSE, a spokesman refused to respond to further queries.
The communications blunder between the HSE and the department has raised concerns about weaknesses in the national action plan to combat the spread of the virus at a time when clusters of the disease are being forecast.
There were also questions being asked last night about how soon the community hall where the band practice took place was used afterwards.
It is understood it was used for activities involving older people yesterday morning.
According to the European Centre for Disease Prevention and Control, the coronavirus can potentially survive in the environment for several days.