FIVE new cases of Covid-19 have been confirmed in Ireland bringing the total number to 18 - but one of the transmissions remains unexplained.

The case involves a man, from the south of the country, who had travelled recently but not from an area known to have been badly affected by coronavirus.

5 Taoiseach Leo Varadkar with Chief Medical Officer Dr Tony Holohan, at Government Buildings today Credit: PA:Press Association

5 A woman wearing a protective mask walks the streets of Paris Credit: Getty Images - Getty

Chief Medical Officer Dr Tony Holohan said at tonight's daily briefing from the National Public Health Emergency Team that they can explain the transmission of all but one of the cases.

He wouldn't be drawn on where the man had travelled from, only that it was not an affected area.

He said: "It wasn't from one of the affected areas that we're aware of, that's still part of the ongoing investigation."

NEW CASES

Among the other four cases is a male in the east of Ireland who travelled from northern Italy.

Another case, a female in the west of Ireland, had close contact with a confirmed case.

A female healthcare worker in the south of Ireland had close contact with a confirmed case, while a female case in the south of the country travelled from northern Italy.

Meanwhile, a fourth case of coronavirus has been confirmed in Northern Ireland.

The person is an adult who had recently travelled from Italy and is linked to a previously confirmed positive case.

Dr Holohan said that each of the cases in the Republic of Ireland are in a hospital environment but would not disclose if any were currently in ICU units.

Dr Ronan Glynn said it is likely that staff have been asked to self-isolate across a lot of hospitals in recent weeks, but said they do not have cumulative figures on this.

Dr Holohan said the "risk of acquiring it in the community is very low", but said it is inevitable there will be more confirmed cases on the island.

OUTBREAK FEARS

Earlier today it was warned coronavirus outbreak could affect 20 per cent of the population of Ireland and could last for two years, a top doctor has warned.

Professor Sam McConkey told how if Irish people had the same kind of interactions as passengers on board the Diamond Princess cruise ship, 20 per cent of people could be diagnosed with Covid-19.

The UL Hospitals Group has announced an "extraordinary" three-county visiting ban on all six of its sites, as a precautionary measure to minimise the spread of Covid-19.

The visitor ban is in place at University Hospital Limerick, University Maternity Hospital Limerick, St John’s Hospital, Croom Orthopaedic Hospital, Nenagh Hospital and Ennis Hospital.

Public health authorities are “working rapidly” to identify contacts of a doctor and his family who are being treated for coronavirus in University Hospital Limerick.

The doctor, his wife and their two children, have been put into isolation bays at UHL.

HSE ADVICE The risk of catching coronavirus in Ireland is still low to moderate, but this could change, the HSE states. Contact HSE helpline: 1850 24 1850 from 8am to 8pm from Monday to Friday and from 10am - 5pm Saturday to Sunday. HSE advice states you can help to protect yourself from Covid-19 by: Washing your hands properly and often

Covering your mouth and nose with a tissue or your sleeve when you cough and sneeze.

Putting used tissues into a bin and wash your hands.

Cleaning and disinfecting frequently touched objects and surfaces.

Trying to avoid close contact with people who are not well.

Following the travel advice from the Department of Foreign Affairs.

Do not touch your eyes, nose or mouth if your hands are not clean.

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And Youghal in Co Cork has become the first town to scrap their St Patrick's Day parade because of the coronavirus.

More than 60 members of staff at Cork University Hospital have been asked to self-isolate after a Covid-19 case via community transmission was discovered at the hospital.

The Department of Health's Chief Medical Officer last night called for a "national effort" in the fight to combat coronavirus.

5 People wear face masks on Times Square after further cases of coronavirus were confirmed in New York City Credit: REUTERS

5 A woman wearing a protective mask walks the streets of Paris Credit: Getty Images - Getty

5 Covid-19 is spreading in Ireland Credit: AFP or licensors