It’s mid-2021, and people arrive at the airport, or line up to attend a concert or a baseball game. They pull out their phones and tap an app that shows whether they’ve had a coronavirus vaccine, or perhaps a test, and breeze through the gates. That’s the brave new world businesses are contemplating as humanity embarks on the biggest mass-vaccination program in history. On Dec. 2 the U.K. became the first country to approve the Pfizer Inc. and BioNTech SE vaccine, followed by the U.S., Canada, and others. Yet even with the end of the pandemic in sight, governments and corporations will have to negotiate some unprecedented logistical, technological, and legal challenges in the months ahead. Until late spring, doses will be in short supply, which means the immediate future will be defined by the haves and the have-nots: people emboldened to leave home with their vaccine- or disease-induced immunity and those who are still waiting in line for a shot in the arm. There’s increasing talk about using so-called immunity passports to get economies moving again. With no time to waste, governments in the U.S. and the U.K. are moving ahead with decidedly low-tech solutions such as paper vaccination cards. Nadhim Zahawi, the U.K.’s minister for vaccine deployment, sparked an outcry in late November when he said that restaurants, bars, cinemas, and sports venues could ask people to demonstrate proof of vaccination before entering. That raised the specter of a two-tiered society, forcing Zahawi to walk back the idea. Alan Joyce, the chief executive officer of Qantas Airways Ltd., ignited a global debate about immunity passports last month when he said proof of vaccination would be a condition for travelers entering or leaving Australia on its planes. He’s discussed the idea with other airlines, and it’s likely to become a pre-boarding requirement around the world, he said during a TV appearance. For now, there’s no international system for verifying that someone has had a jab. The World Health Organization is working on an e-vaccination certificate. But this will take time, because there are myriad issues to sort out. Here’s one: If countries require vaccination for entry—the likely scenario for any future travel—what happens when a Russian citizen lands in London claiming to have been inoculated with the Sputnik V vaccine, which hasn’t been approved in the U.K.? There are further reasons to proceed with caution. Scientists still don’t know how long the leading vaccines provide protection, or if they stop transmission of the virus. The frontrunners are highly effective in preventing disease, but it’s unclear whether vaccinated individuals might still be infectious. “Vaccination may protect the individual but not their contacts,” says Emily Hyle, an infectious disease physician at Massachusetts General Hospital in Boston. “We need more information before using vaccination status to change guidance about masking and social distancing.” The yellow fever vaccine is the only immunization required for travel to certain countries under the WHO’s International Health Regulations, a rule familiar to hardened travelers who end up accumulating a collection of the tattered yellow vaccination booklets. WHO would have to modify its rules for a Covid-19 vaccine—a long, fraught process that would involve all 194 members. Governments are banking on enough people being eager to get a shot so they can confidently resume their daily lives, enabling them to sidestep the need for mandates. “All of us who work in public health would rather avoid mandatory vaccination,” Mike Ryan, head of the WHO’s emergencies program, said at a briefing in Geneva in December. “We’re much better served to present people with the data, with the benefits, and let people make up their own minds.” Subscribe to our YouTube channel: https://bit.ly/2TwO8Gm Bloomberg Quicktake brings you live global news and original shows spanning business, technology, politics and culture. Make sense of the stories changing your business and your world. To watch complete coverage on Bloomberg Quicktake 24/7, visit http://www.bloomberg.com/qt/live, or watch on Apple TV, Roku, Samsung Smart TV, Fire TV and Android TV on the Bloomberg app. Have a story to tell? Fill out this survey for a chance to have it featured on Bloomberg Quicktake: https://cor.us/surveys/27AF30 Connect with us on… YouTube: https://www.youtube.com/user/Bloomberg Breaking News on YouTube: https://www.youtube.com/c/BloombergQuickTakeNews Twitter: https://twitter.com/quicktake Facebook: https://www.facebook.com/quicktake Instagram: https://www.instagram.com/quicktake