Three travellers staying in mandatory hotel quarantine have tested positive for Covid-19 and have been moved to a 'Covid wing' within the Crowne Plaza Hotel near Dublin Airport.
The positive cases were detected as part of the first tests of visitors who arrive into the mandatory quarantine facility, a HSE source has confirmed.
These are the first cases of the disease to be detected since the mandatory hotel quarantine system came into effect last week.
Guests undergo testing on the first and 10th days of their 12-night quarantine.
The number of travellers facing mandatory hotel quarantine looks set to rise substantially after it was recommended that a further 43 countries should be added to the high-risk country list.
The United States and EU countries including France, Germany and Italy are on the list of additional countries that the Travel Expert Advisory Group has recommended should be added to the list for mandatory hotel quarantine for travellers arriving into the State.
There are already 33 countries on the so-called “category two” list from which travellers must quarantine for 12 nights on entry into the country.
The National Public Health Emergency Team (Nphet) must consider the list of additional countries and the Minister for Health must consult with the Minister for Foreign Affairs on the list.
A decision will made on these countries later this week.
The recommended list is based on countries where there are concerning coronavirus variants in circulation or where Covid-19 cases are higher than 500 per 100,000 people.
Travellers face a fine of €2,000 or a month’s imprisonment if they fail to adhere to the rules.
The possibility of more than double the size of the list raises political, diplomatic and logistical complications as it tightens travel restrictions with major EU countries where many Irish citizens are living.
The return of travellers from these countries could put significant pressure on the capacity of the hotel quarantine system to cope given the numbers that could return in the summer.
The first four hotels being used for mandatory quarantine are the Crowne Plaza Dublin Airport in Santry, the Holiday Inn Express Dublin Airport, Clontarf Castle hotel and the Hard Rock Hotel in Dublin city centre. The hotels are run by Tifco, the country's second largest hotel operator.
The cost of the quarantine is €1,875 per person.
There are about 20,000 Irish citizens living in France and 16,000 in Germany so the return of even a proportion of these people returning could strain the capacity of quarantine hotels.
The introduction of strengthened travel restrictions on major EU countries could pose diplomatic issues for the Government, though one source said that the German government’s decision to tighten border controls this week could make further restrictions easier.
Currently, Austria is the only country in the European Union or Europe on the list of countries from which travellers must undergo mandatory hotel quarantine.
