Governments and airlines are quickly moving forward to implement paper and digital COVID passports that will be required for travel. This article discusses how the United Kingdom has already contracted with firms to develop the passport systems:
And this article reports that Singapore Airlines is now requiring COVID passports for travel:
I expect COVID passports and likely vaccination requirements to be the norm for travel…hopefully market competition will provide strong incentives for some travel companies to provide services (legally and perhaps underground) without such requirements for the many who do not wish to comply with such coercive actions.