LONDON (AP) — Britain is removing Portugal from its list of COVID-safe travel destinations, meaning thousands of U.K. residents currently on vacation there will have to quarantine on return. Transport Secretary Grant Shapps said the “difficult decision” was prompted by rising case rates in Portugal and worries about new versions of the coronavirus that could prove resistant to vaccines. The change will take effect Tuesday. Portugal had been the only major tourism destination on the U.K. government’s “green list” of places that can be visited without a post-travel quarantine requirement. Britain is also adding seven countries, including Afghanistan, Costa Rica and Egypt, to its “red list” of places to which only essential travel is permitted.