The European Union has launched its digital COVID certificate system, designed to help citizens travel more freely across the 27-nation bloc and open up summer tourism.
WHAT IS IT?
The EU digital COVID certificate, which can be on a smartphone or printed out, takes the form of a QR code, which indicates whether a traveller has been fully vaccinated against COVID-19, has received a recent negative test result, or has immunity due to recent recovery from an infection.
It is designed to be free of charge, issued and valid in all EU countries, and is set out in the national language and in English.
The system also extends to non-EU countries of the border-free Schengen zone - Iceland, Liechtenstein, Norway and Switzerland.
The system is active from Thursday, with a six-week phase-in period for EU member states not yet ready.
HOW IT WORKS?
The certificate system cleared the approval process in mid-June, but EU countries still had to decide how it should be used.
They agreed people who have been fully vaccinated for 14 days should be able to travel freely from one EU country to another.
About 40 per cent of EU adults are fully vaccinated.
Restrictions for other travellers should be based on the degree to which the country they are coming from has COVID-19 infections under control, based on a colour coding system set by the European Centre for Disease Prevention and Control.
For travel from a green zone, there should be no restrictions, from orange - potential for a test; for red - a possible quarantine; and non-essential travel discouraged for 'dark red'.
Children aged 12 or over could be tested, but would only quarantine if an adult accompanying also had to.
Border policy as a whole, though, is a matter for individual EU countries, so they can still set their own rules.
Airlines have warned of chaos and hours-long queues unless countries better co-ordinate the rollout.
Within certain rules, EU member states will also be able to hit an 'emergency brake' to bar travellers from a region showing a spike in more infectious variants of the disease.
The European Commission said it had learned from Berlin that Germany was invoking such a brake in its declaration that Portugal is a "virus-variant zone".
It means a mandatory two-week quarantine even if travellers are fully vaccinated or test negative.
The Commission has warned Berlin the restrictions "do not seem fully aligned" with the EU-wide recommendations.