The US Centers for Disease Control has issued a Level 4 notice for Ireland, advising that travel here should be avoided.
The CDC issued the new recommendation, which advises against travelling to 16 destinations, including Ireland, even if fully vaccinated against Covid-19.
It states that "because of the current situation in Ireland, even fully vaccinated travellers may be at risk for getting and spreading Covid-19 variants".
It added that travellers should "follow recommendations or requirements in Ireland, including wearing a mask and staying 6 feet apart from others".
The other countries also ranked at Level 4 are Andorra, Curacao, Gibraltar, Greece, Guadeloupe, Iran, Isle of Man, Kazakhstan, Lesotho, Libya, Malta, Martinique, Saint Barthelemy, Saint Martin and the US Virgin Islands.
Since March last year, non-US nationals or permanent residents, with some exceptions, have not been permitted to travel to the US if they have been in Ireland and a number of other designated countries in the previous 14 days.
Under current guidelines, people arriving from the US to Ireland must complete a Covid-19 Passenger Locator Form and have valid proof of vaccination or recovery, or have a negative PCR test within 72 hours of arrival.
No travel-related testing or quarantine is required for people arriving into Ireland from the US who have valid proof of vaccination.
All passengers who are not vaccinated must present a pre-departure negative PCR test (taken within the 72 hours prior to arrival in Ireland).
They must also home quarantine for 14 days on arrival from the US but can exit quarantine after five days following a negative PCR test.