Downing Street sources told The Guardian ministers were considering a change in the rules on travel so that eligible people who had turned down a third dose would face quarantine and testing if they went abroad. The change was said not to be imminent.
Official guidance said the government was “looking at whether and how booster vaccinations could be included in the NHS Covid pass for travel”.
Currently, all over-50s, health and social care workers and the clinically vulnerable can receive boosters six months after their second dose.
Booking systems are being changed to allow people to arrange their appointment a month before they have the shot.
More than 10 million UK people have already had the top-up.
