The new rules went into effect at 4 a.m. on Monday, but they have yet to be met through a reciprocal relaxation of restrictions for travelers from the UK.
The new rule applies to England, Scotland, Wales and Northern Ireland.
Transport Secretary Grant Shapps said: “We are helping to reunite people living in the United States and European countries with their family and friends in the United Kingdom. “
Previously, only travelers who received both doses of the coronavirus vaccine in the UK could enter from an amber country – the US and most of the EU – without self-isolating for the required 10 days.
But the isolation exemption will now cover people vaccinated in the US and the EU.
Arrivals from France are the exception, isolation remaining mandatory regardless of vaccination status.
US citizens must have a vaccination card, while EU citizens need the block “green pass” indicating their vaccination status.
Paul Charles, Managing Director of travel consultancy The PC Agency, said: “The importance of this decision cannot be overstated.
“This will inject vital money into the travel economy and help save the rest of the summer.
“Incoming visitors bring billions of pounds to the economy and they can be safely welcomed.
“This is particularly good news for our airlines who need to fill their seats across the Atlantic. “
Also on Monday, international cruises from England are allowed to resume, after a forced break of 16 months.
However, most companies will not take passengers immediately for logistical reasons.
Follow the Daily podcast on Podcasts Apple, Google Podcasts, Spotify, Streamer
Meanwhile, there are fears that the government is considering creating an amber watchlist, which would include countries at risk of being redlisted in the short term.
Arrivals from Red List countries must spend 10 days in hotel quarantine at a cost of £ 1,750.
There is already a Green Watch List, which includes countries on the Green List that are at risk of turning orange.
According to The Daily Telegraph, Mr. Shapps is against the idea and instead is pushing for travel to be more open.
Ministers will meet on Thursday to decide on travel rules that will be in place for most of August.
The Transportation Department said it would not comment on the “speculation” when asked about a possible Amber Watchlist.