Travellers from mainland Portugal to England will have to quarantine from 04:00 BST on Saturday, just weeks after the country was put on the safe list.
Hungary also lost its exemption in the latest round of quarantine changes; so did Reunion and French Polynesia, but vanishingly few British travellers will be affected.
Sweden has gained quarantine exemption.
What has changed?
The transport secretary, Grant Shapps, tweeted: “Data shows we need to remove Portugal (minus the Azores and Madeira), Hungary, French Polynesia and Reunion from the Travel Corridor list to keep everyone safe.“
If you arrive in England from these destinations after 4am Saturday, you will need to self-isolate for 14 days.”
Portugal is now in the same Foreign Office risk category as central Kabul and parts of Somalia.
The country was given quarantine exemption only three weeks ago. Scotland placed the whole country on its quarantine list a week ago, while Wales insists anyone returning from the mainland – but not the islands – self-isolates for two weeks.
Where does that leave holidaymakers who are there?
On the beach or in the bar. Or rushing to the airport.
When the UK government reimposes quarantine on a country, it does not say “come home now”.
But many people will choose to do so at their own expense.
For people who opt to stay – perhaps because they can’t afford the fares that are being charged – holidays will continue.
Holidaymakers on longer stays, of two or three weeks, may find there are changes to flights coming home as airlines cut flights to reduce losses – because demand will dry up.
What options are there for beating the deadline?
Air fares from Faro (serving the Algarve), Lisbon and the northern city of Porto have been rising sharply as Portugal’s infection numbers increased.
