Europe's tourist industry has taken a beating during this pandemic, spurring Denmark to introduce vaccine passports as a way to boost travel. The digital documents will provide proof of a traveler's COVID-related health, eliminating the need to quarantine upon arrival in a new country. But opponents fear this could create billions of second-class citizens. Malcolm Brabant reports. PBS NewsHour is supported by - https://www.pbs.org/newshour/about/funders