Ministers are discussing plans to make Covid vaccine booster shots compulsory for care home staff and quarantine-free travel abroad, it is reported.
Health Secretary Sajid Javid already plans for booster shots to go to vulnerable groups and over-50s from September.
Now ministers have suggested the "logical" next step would be to make these booster jabs a condition of keeping a person’s vaccine status up-to-date.
One source told the Mail on Sunday: "The assumption is you will be required to have the most up-to-date health passport.
“So if the advice is to have a booster six months after your second jab, then that is what you will need."
According to the newspaper, that would mean travel benefits for some double-jabbed Brits - for instance, being spared quarantine on return from amber list countries - may only continue if they get triple-jabbed.
Likewise, the requirement for England’s care home staff to be double-jabbed from autumn could extend to booster jabs too.
But talks appear to be in very early stages, as one senior government source said they did not recognise the plans.
It has not yet been confirmed whether or when healthy under-50s will get booster shots in the UK. That could complicate any plan to include boosters in a ‘vaccine passport’.
Jabs are being rolled out to under-18s this week - with more pressure on health chiefs to extend the roll-out to over-12s ahead of schools going back in September.
All 16 and 17-year-olds in England will be offered their first Covid jab by August 23, under a new target set by Mr Javid.
More than 75% of UK adults have now received two Covid jabs.
A total of 40.4million people have now received both doses, while another 7 million have only had a single dose.
Health chiefs expect to deliver millions of booster shots in England between September 6 and December 17, at the same time as flu jabs.
The Joint Committee on Vaccination and Immunisation (JCVI) previously suggested boosters will go first to immunosuppressed and extremely vulnerable over-16s; care home residents; frontline health and care workers; and all over-70s.
Boosters would then go to all over-50s, plus all over-16s in a flu or Covid risk group, and any adults who share their home with an immunosuppressed person.
The JCVI did not rule out extending booster shots to healthy under-50s but said in June it was too early to make a decision.
The group said on June 30: “As most younger adults will only receive their second COVID-19 vaccine dose in late summer, the benefits of booster vaccination in this group will be considered at a later time when more information is available.”
Mr Javid told journalists last week: “When it comes to booster jabs we are waiting for the final advice from JCVI, that’s our group of independent clinical advisers.
“When we get that advice we will be able to start the booster programme, but I anticipate it will begin in early September, so I’m already making plans for that.”
A government spokesperson said: “We are preparing for a booster programme to ensure those most vulnerable to COVID-19 have protection extended ahead of winter and against new variants.
“Any booster programme will be based on the final advice of the independent Joint Committee on Vaccination and Immunisation (JCVI). Until we receive the independent JCVI advice no decisions can be made on wider requirements for those who receive booster jabs.
“The phenomenal vaccine rollout is building a wall of defence across the country, with over 66,900 hospitalisations prevented and more than 84,000 lives saved.“
