© AFP/Hector Retamal
The UN health agency's emergency committee has not advised the WHO that immunity certification should be a "prerequisite of travel," Mike Ryan said during a news briefing on Monday, after being asked about vaccine passports.
"That is because, number one, vaccines are not widely available. [It] would actually tend to restrict travel more than permit travel," Ryan added.
"Secondly, we don't have enough data right now to understand to what extent vaccination will interrupt transmission."
The official's comments come at a time when multiple countries and airlines are already pursuing so-called vaccine passports, which they say would allow travelers to enter countries without the need to quarantine or be tested for Covid-19 at points of entry.
Iceland and Poland have both launched vaccine passport programs, while Denmark, Sweden and Spain are set to follow suit.
European Commission President Ursula von der Leyen supports an EU-wide vaccine passport scheme, and US President Joe Biden is also reported to be looking at a similar strategy.
The International Air Transport Association, which represents 290 airlines worldwide, is currently working on a digital vaccine passport.
Meanwhile, airlines including Qantas, Emirates, Etihad and American Airlines are working on their own schemes, and other operators, including United Airlines, Lufthansa, and Virgin Atlantic will use the CommonPass health app.
The CommonPass platform, which is backed by the World Economic Forum, allows travellers to digitally access their Covid-19 testing and vaccination records so that they are able to provide proof of their health status at borders.
Comment: It's likely the ability to travel freely around the world will be restricted going forward. Show your vaccine passport, or forget about flying to visit a loved one or to take a vacation.