The UK has updated the list of countries on its green travel list, with upgrades for Malta, Madeira and the Balearic islands, as well as some Caribbean islands.
There are also plans to later this year drop quarantine requirements for double-vaccinated passengers.
What are the latest changes to the green list?
Fourteen countries and territories will be cleared for quarantine-free travel from 4am BST on Wednesday.
Unlike the amber list, green list travellers do not need to isolate on their return to the UK.
The new additions to the green list are Malta, Madeira, the Balearic Islands, Israel and Jerusalem, Bermuda, the Cayman Islands, Montserrat, and Caribbean Islands Antigua, Barbuda, Dominica, Barbados, Grenada and the British Virgin Islands.
What is the green watch list?
All the new additions except Malta will appear on the green watch list, meaning they are at risk of suddenly being moved to amber.
The government is advising people travelling to green watch list countries to "take extra consideration" when booking holidays because "if there is a sudden change in conditions, a country or territory may be moved between lists without warning".
UK Transport Secretary Grant Shapps said people should be aware the Covid situation could change quickly in any country to which they are travelling.
“At least people understand that's where we’re coming from,” he told the BBC. “We have this information and we think it’s right that other people have it as well.”
What happens if a country turns from green to amber?
Travellers arriving from a former green list country that has moved to amber will have to quarantine on arrival in the UK and take several Covid-19 tests.
The minimum requirement is 10 days of home quarantine but early release on day five is allowed with proof of a negative test.
As seen previously, unexpected changes can lead to passengers rushing to organise a flight home before the updated rules take effect.
What are the plans for double-vaccinated travellers?
Prime Minister Boris Johnson said there was a “real opportunity” to open up travel for double-vaccinated travellers.
However, the government has not given a specific timeframe for the plan, saying only “later in the summer”.
Mr Shapps said fully vaccinated passengers could effectively treat amber countries as green, meaning they would not need to quarantine.
He said there were several hurdles to overcome in the next few months, including how to verify the vaccination status of non-UK residents.
“What do you do for people from elsewhere, where perhaps they don't have electronic records at all?" he said.
"The US is a good example, there are probably 50 different systems in different states and many of them are paper-based. There are lots of things to work through."
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He said there were also concerns about how to treat under-18s, who are not eligible to receive Covid-19 vaccines in the UK, and older people who refuse to take the vaccine.
"We’ve also got some people who will never be vaccinated. There are obviously issues over how you treat those people fairly," he said.
Who decides if a country is green, amber or red?
The decision is taken by ministers, who are informed by the Joint Biosecurity Centre, which looks at the Covid situation in each country.
The JBC examines the infection rate, testing capacity, quality of data, the risk posed by variants and genome sequencing capabilities.
The lists are reviewed every three weeks.
What happens to travellers who do not quarantine?
All passengers, whether vaccinated or not, must continue to abide by quarantine rules for returning to the UK from an amber list country.
The recommendation is still that people should not travel to amber list countries.
Anyone who does not quarantine at home after international travel can be fined £1,000 ($1,389), which may rise to £10,000 for repeat offences.