The Times reports that Greece is ready to break with the European Union’s stance on a resumption of international tourist travel.
According to the paper, Greece is exploring what certification might be required, as well as the logistics of ensuring its tourism workforce is vaccinated and ready.
By contrast, the EU is hopeful of a unified resumption of non-essential foreign travel from outside the union.
The World Health Organization, meanwhile, has warned requiring vaccination for travel would breach international health rules.
Prime minister Boris Johnson has promised a review of vaccine certification in England, which will be lead by cabinet office minister Michael Gove.
The government has previously ruled out a formal vaccine passport regime, but has hinted certification could be introduced to open up certain parts of the economy.
Vaccines minister Nadhim Zahiwi, meanwhile, has said that if and where required by destinations, vaccine certification could be facilitated, as has health secretary Matt Hancock.
Greece, Israel and Cyprus have formed a travel bubble based on vaccination, with Greece repeatedly hinting it could waive any Covid testing requirements for those who have been vaccinated.
The Telegraph reports other destinations, including Thailand, could scrap quarantine for vaccinated visitors.
Several travel operators including Saga Cruises and Crystal Cruises, have said they will require guests to be fully vaccinated to travel with them.
Speaking during a school visit on Tuesday, Johnson said there were ethical issues to consider, the BBC reports. "We can’t be discriminatory against people who can’t have the vaccine."
The Times, though, further reports that an existing NHS appointment app for smartphones could be converted into a digital Covid vaccine certificate.
Gove’s review is due to report before 21 June, the date fixed for England’s economy to reopen fully; Johnson on Monday (22 February) set out his roadmap for the country to emerge from the current Covid lockdown, which could see domestic leisure travel resume from 12 April and international travel from 17 May, subject to a Global Travel Taskforce review.
Several other travel stakeholders are exploring some form of vaccine certification, including Iata, which said on Tuesday its Travel Pass app will be ready for launch in the coming weeks.
Singapore Airlines and Qatar Airways are trialing the app, with Air New Zealand also reportedly keen to look into its use. Etihad has pledged to introduce it "in the first quarter".