Vaccine passports which enable people who have had the coronavirus jab to travel abroad are being considered by the UK government and across the globe.
The EU has made plans to rollout Digital Green Certificates in the summer, subject to approval of European Parliament and EU member states. These certificates propose to allow freedom of movement across the EU if you've been vaccinated against Covid-19, have recovered from the illness, or tested negative.
The UK government is considering introducing an international system - similar to the yellow fever card, which is required to enter countries such as Brazil and Uganda.
Cyprus has just announced it'll allow vaccinated British tourists into the country from May 1 if they can prove it, without the need for quarantine or testing. However, holidays abroad are banned until May 17 at the earliest and our government is yet to say if or how we'll be able to prove we've been inoculated. .
Currently UK travellers returning from high-risk countries are required to pay £1,750 to quarantine in a hotel. Those caught lying about their movements could face a £10,000 fine or 10 years in jail.
It is hoped the vaccine passport would allow people who have received their jabs to travel freely without the need for quarantine.
It is not currently known how the digital passport or certificate for the Covid-19 jab would work in the UK.
The European Commission however has proposed how its Digital Green Certificate might work. The proposal is focused on EU nationals, and those residing and working in the EU. However it does say those 'staying' in the EU who hold a Digital Green Certificate should also be exempt from free movement restrictions. That may mean people in the UK can travel to the EU for visits and holidays using the Green Pass - but this is still unclear.
The certificate will be stored on your mobile, or you can request a paper version, but both will feature a QR code. This code will contain all essential information (such as test results and vaccine certificates) as well as a digital seal and secure key.
When scanned, the person checking the code will be notified if it's authentic and has been issued by a valid issuing body - such as a hospital or test centre. It is important to note the European Commission says when your code is checked through the specially built gateway, no personal data will pass through this. Additionally, your data cannot be retained in the countries you visit. Data being exposed or shared has been a key reason for people opposing vaccine passports.
Other countries or airlines could be satisfied with a certificate or letter from your doctor, as long as it contains all the essential information.
Most have welcomed the idea as the best way to kick-start travel again.
Greece and Israel already have digital vaccine certificates in place and Greece and Cyprus plan to admit those from Israel with Covid green certificates.
Iceland also plans to accept digital vaccine certificates from those in EU and Schengen countries, but it already will accept those who can prove they have antibodies with an antigen test.
Cyprus has also said it will allow Brits to enter from May 1 if they can prove they've been vaccinated. However, they've not said it's mandatory. If the UK is on its green list it will allow you to enter with proof of a negative Covid-19 test too.
The EU's Digital Green Certificate - if approved - will make it easier for EU member citizens to travel, but there is no mention currently on whether third country nationals, such as Brits, will be allowed in using a similar system.
Whilst countries may be considering vaccine passports, it doesn't mean they plan to make the vaccine a requirement for travel, however.
Critics argue that a health passport will infringe on civil liberties and restrict those who have refused a vaccine. Other have voiced concerns around data privacy and the protection of travellers' personal information. A petition urging the government not to roll out the scheme has attracted more than 86,000 signatures.
While the UK government has suggested the passport would not be mandatory, other countries could still decide to make it an entry requirement - restricting travel to those deemed a transmission risk.
However, the UK could be at an advantage as it races ahead of mainland Europe - and most of the world - with its vaccine rollout.
The Seychelles was the first nation to announce it would welcome vaccinated travellers from across the world.
The Greek prime minister has said he could allow British holidaymakers to visit as early as May if they have received two doses of any approved jab.
Greece may also offer similar freedoms to people who can prove they have recovered from the virus or can show a negative Covid-19 test. The pandemic has been devastating for the country, with tourism making up a fifth of its economy.
Since Greece made this announcement, the EU has laid out its plans to roll out Digital Green Certificates across the whole of the EU (see above).
Countries including Iceland, Georgia and Poland have also lifted restrictions for those who can provide proof of vaccination.
If your destination has similar rules, details should be listed on the Foreign, Commonwealth and Development Office (FCDO) website. It's not yet known whether producing a negative test result for coronavirus upon arrival will be sufficient for travellers who can't or won't have the jab.
Similarly, some airlines and holiday companies are trialling their own health passports to get travel moving again.
Last month, Saga announced that it requires all holiday and cruise customers to be fully vaccinated before travel. Only those who have received both jabs at least 14 days before departure, or the medically exempt, will be allowed to travel.
Passengers will also need to take a Covid test at the departure terminal. The over-50s provider, which has suspended all operations until 1 May, says 95% of its customers are in favour of the policy. And anyone who is unable, or unwilling, to get the Covid-19 vaccine can request a date change or a full refund.
Qantas will also demand proof that passengers have been fully vaccinated before travel, unless they are exempt for medical reasons.
The Australian airline is set to trial the Travel Pass system developed by the International Air Transport Association (Iata). The contactless app will allow passengers to share Covid-19 health information with airlines and border authorities. Iata says the data will be sent by certified labs and test centres in a format that is secure. It has also confirmed it has trialled a rival app known as the CommonPass system.
However, travellers should expect to continue wearing masks and social distancing on flights, even after getting immunised.
It is no surprise that the carrier is taking a stringent approach. Australia's borders have been closed to international travellers since March, with those returning home required to quarantine in a hotel for 14 days. The country has reported less than 30,000 confirmed cases as a result.
Singapore Airlines, Emirates, and Etihad Airways have also partnered with IATA's Travel Pass, with Singapore Airlines planning to integrate the functionality into its own mobile app this summer.
British Airways is the first UK airline to trial a travel health 'passport' which stores coronavirus test results and proof of vaccination.
One app it is testing is called VeriFLY and it checks the passenger's health information against the destination's entry requirements and returns a 'fail' or 'pass' message.
It was rolled out on BA's transatlantic routes on 4 February and for passengers on all inbound international flights to the UK from February 15. It is also being trialled by American Airlines. However, BA insists that use of the app is not mandatory.
Alongside this, British Airways will also ask customers travelling to India to trial its own system on 'Manage my Booking'. These passengers will be given the option to upload a negative Covid-19 test result and any other relevant documentation. It will then be checked by BA to ensure the customer has everything they need to be permitted entry to India, before allowing them to check in online.
Lufthansa, JetBlue, Virgin Atlantic and Cathay Pacific have signed up for the CommonPass, after a successful trial by United Airlines.
The app, created by Swiss not-for-profit Commons Project Foundation and the World Economic Forum, allows travellers to upload their Covid-19 test results or proof of vaccination which generates a certificate in the form of a QR code.
The slogan for CommonPass is: 'Share your current health status so you can safely return to travel and life.' Again, it is thought to a voluntary scheme rather than a mandatory condition of boarding.
Available on the Ryanair app, the Covid-19 Document Holder allows travellers to upload their travel documents, including negative test results and vaccination certificates.
Because there is no common travel passport just yet, it simply acts as a digital wallet to hold all the documents you might need to gain entry to a country in one place after uploading, rather than carrying pieces of paper.
Cruise lines are already insisting that passengers take a test before boarding and once on board. Which? Recommended Provider Viking Ocean Cruises says it expects to initially test both guests and crew on a daily basis.
It therefore seems likely that some cruise lines will consider making vaccines mandatory.
Celebrity and Royal Caribbean told us: 'Guests must ensure they are medically and physically fit for travelu2026in many cases inoculations are recommended, but in some circumstances, they are required.'
No travel insurance policy covers disinclination to travel, so if vaccines become mandatory at your destination, you won't be able to claim back the costs of your holiday if you decide to cancel.
Refusing a vaccine could also affect your emergency medical cover. Travel insurance policies sometimes contain exclusions relating to vaccinations. That means if you visit a country without getting the NHS-recommended inoculations, you may not be covered if you end up contracting the illness.
As far as we're aware, no similar exclusions relating to the coronavirus vaccine have yet been added to travel insurance policies. But it's something we could see in the coming weeks and months, as many travel insurers do now include cover for catching coronavirus while on holiday.