EXPLAINER: Will you need a 'vaccine passport' to travel?

Airlines and others in the travel industry are throwing their support behind so-called vaccine passports to boost pandemic-depressed travel, and authorities in Europe could embrace the idea quickly enough for the peak summer vacation season.

Technology companies and travel-related trade groups are developing and testing various versions of the vaccine passports, also called health certificates or travel passes.

It is not clear, however, whether any of the passports under development will be accepted broadly around the world, and the result could be confusion among travelers and disappointment for the travel industry.

Here are some key questions about the health credentials.

WHAT IS A VACCINE PASSPORT?

It is documentation that shows a traveler has been vaccinated against COVID-19 or recently tested negative for the virus that causes it.

The information is stored on a phone or other mobile device that the user shows to airline employees and border officers. The Biden administration and others want a paper version available too.

WHO IS DESIGNING THEM?

The trade group for global airlines, the International Air Transport Association, is testing a version it calls Travel Pass. IBM is developing another, called a Digital Health Pass. There are several other private-sector initiatives.

Some countries are getting involved and using the passports beyond air travel. Israel is using a new “green passport” to ensure that only people who have been vaccinated or recovered from COVID-19 can attend public events such as concerts. Denmark expects to launch a pass that will let vaccinated people travel with fewer restrictions.

WHY DO TRAVEL COMPANIES WANT THEM?

International air travel has collapsed during the pandemic, as countries impose restrictions such as quarantines or...