Cyprus and Lithuania have been removed from the Government’s list of travel corridors, the Department for Transport has announced.
Travellers arriving in the UK from those countries after 4am on Sunday must self-isolate for 14 days due to a rise in coronavirus cases.
The decision will affect families on half-term breaks in Cyprus who are booked on flights home later on Sunday.
No countries have been added to the list of travel corridors this week.
The travel industry was given a much-needed boost when the Canary Islands were added last week.
The DfT said there has been a “consistent increase” in Covid-19 cases in Cyprus over the past two weeks, with a “79% increase in total cases” over that period.
In Lithuania, the number of new coronavirus cases per week has increased by 47% over the same period.
Germany maintains its quarantine exemption despite recording 107 cases per 100,000 people in the past week.
The Government is believed to be using a rate of 100 as the threshold above which it considers triggering quarantine conditions.
The UK’s own rate is 230.
The DfT said a “range of factors are taken into account” using data from the Joint Biosecurity Centre and Public Health England.
These include case numbers, testing capacity, test positivity and the “potential trajectory of the disease in the coming weeks”.
A spokeswoman for travel trade organisation Abta said: “The industry’s optimism from last week’s good news has been short-lived following the removal of Cyprus from the travel corridor list.
“Last-minute changes like this further erode consumer confidence in overseas travel and serve as a stark reminder of the urgent need to introduce testing to cut quarantine.”
Paul Charles, chief executive of travel consultancy The PC Agency, said: “Cyprus has seen a 400% increase in infections in the last two weeks but no mortalities since early October.
“It’s bizarre that the UK Government thinks Cyprus is more of a risk to Brits than Germany.
“The decisions made by the Joint Biosecurity Centre are now highly questionable.
“Germany is moving into mini-lockdown, seen a surge in infections in recent days, yet it’s deemed lower risk than Iceland.
“And it’s indefensible that Africa still has no travel corridor.”