A new approach to air travel across Europe has come into operation.
As part of the European Union's traffic light system, countries and regions within those countries, will be categorised as green, orange or red depending on Covid-19 risk levels.
The European Centre for Disease Prevention and Control will publish a weekly map determined by the 14-day incidence and positivity rates of the disease.
People arriving in Ireland from red regions are required to restrict their movements for two weeks.
Passengers from orange regions can avoid the restriction - if they have a negative coronavirus test result taken no earlier than three days prior to departure.
Travellers from green regions can enter the State without restricting their movements or undergoing a test.
Currently, only Greenland is in the green category, with Norway, Finland and parts of Greece orange while all others areas are red.
Anyone arriving from Denmark must restrict their movements for two weeks regardless of the traffic light rating, over concerns about the new strain of Covid in mink there that has spread to humans.
Under the new system, passengers travelling on certain essential functions do not have to restrict their movements.
This includes essential workers, journeys for imperative business or family reasons (for example, attending a funeral) and essential medical reasons for travel.
The Government has also said a mechanism is due to be in place by December whereby people coming from red regions can be tested here after five days.
And with Ireland at Level 5, the current advice remains that there should be no non-essential international travel.
Aer Lingus said in a statement that it welcomes the introduction of a testing regime to facilitate the European traffic light system.
"It represents a positive initial step towards facilitating increased safe international travel, which is critical to the Irish economy."
Aer Lingus said it believes that over time, it should result in a "meaningful increase" in safe international travel and lead to a limited form of random rapid testing for passengers arriving from orange countries or regions, and pre-departure testing for locations classified as red.