Quarantine restrictions are increasingly likely to be imposed on travellers arriving in the UK from Italy, mainland Greece and Sweden, new figures suggest.
Italy is one of the most popular foreign destinations which UK holidaymakers can still visit without needing to isolate for 14 days when they return.
But the country is currently recording a seven-day rate of 25.6 coronavirus cases per 100,000 people.
Greece and Sweden have rates of 22.4 and 20.7 respectively.
A rate of 20 is the threshold above which the UK Government considers triggering quarantine conditions.
Figures have been calculated by the PA news agency based on data collected by the European Centre for Disease Prevention and Control.
The self-isolation requirement is already in place for people arriving in Scotland from Greece, and in the rest of the UK from several Greek islands.
Changes to the UK Government's list of destinations from which arrivals in England do not need to enter quarantine are usually announced every Thursday at 5pm, and implemented the following Saturday at 4am.
The devolved nations have their own exemption lists which are similar but not identical.
The travel industry has been badly hit by quarantine restrictions dampening demand for overseas trips.
But the boss of Heathrow Airport has been told by Boris Johnson that trials of coronavirus testing at airports to potentially reduce self-isolation periods could begin later this month.
Chief executive John Holland-Kaye told magazine Travel Weekly: "We've heard from the Prime Minister that he hopes to go to a trial in the second half of October.
"It would take a couple of weeks to put into practice."
He added: "We can start testing at some scale in the next few months. I would love to have a New York-London pilot up and running by Thanksgiving (November 26). That seems entirely feasible."
A Department for Transport spokeswoman said: "The Government recognises the impact that coronavirus is having on the economy and workers, and has put together an extensive package of financial support to help the aviation sector.
"Work is ongoing with clinicians and health experts on the practicalities of using testing to reduce the self-isolation period for international arrivals."