The Biden administration is working on plans for how to manage credentials that would let people prove they’ve been vaccinated against COVID-19, The Washington Post reported. Often referred to as “vaccine passports,” these credentials could be displayed on free smartphone apps or printed. Many companies say they’ll ask for proof of vaccination before letting people attend concerts or travel.

Organizing a unified system for these types of credentials will be hugely complicated, and the stakes are high: an inconsistent array of options would be confusing and could hurt public health efforts, officials said in a March 2nd meeting of the Federal Health IT Coordinating Council. “A chaotic and ineffective vaccine credential approach could hamper our pandemic response by undercutting health safety measures, slowing economic recovery, and undermining public trust and confidence,” a slide obtained by The Washington Post read.

At least 17 groups are already working on their own versions, including a tech company coalition called the Vaccination Credential Initiative (VCI), the World Health Organization, and the International Air Transport Association. New York state already started using a digital pass developed by IBM. It can show vaccination status or COVID-19 test results, and venues like Madison Square Garden already announced that they’ll use it as part of admission.

Federal officials and groups working with vaccine credentials are grappling with various technical, ethical, and equity issues as the programs move forward. Using vaccination as a ticket to various activities is fraught when vaccines aren’t easily available to everyone, and right now, they’re more accessible in white and wealthy communities. The credential programs will have to have robust privacy protections and be resistant to hacks or forgery. People are already forging paper vaccination cards distributed at vaccination sites.

Officials also have to consider things like future booster shots and the duration of vaccine protection. The Biden administration says it will have more information available on its approach to overseeing vaccine credentials soon. Almost 30 percent of the US population has at least one dose of a COVID-19 vaccine already, but it’s important to move deliberately on this project, an official told The Washington Post. “This has a high likelihood of being either built wrong, used wrong or a bureaucratic mess,” the official said.