Dr. Anthony Fauci told CNN that the government is considering multiple different options for when it comes time to ease social isolation guidelines. One of those ideas involves having people carry identification cards to indicate whether or not they have immunity to the COVID-19 virus.

As Politico reports, the head of the National Institute of Allergy and Infectious Diseases says the government wants to be able to identify those who have been infected as the economy re-opens in order to prevent a renewed surge of the novel coronavirus.

When asked by CNN if immunity cards were under consideration, Fauci confirmed that they were.

“You know, that’s possible,” he said. “I mean, it’s one of those things that we talk about when we want to make sure that we know who the vulnerable people are and not. This is something that’s being discussed. I think it might actually have some merit, under certain circumstances.”

For the idea to be implemented, an antibody test will need to be made available to all Americans. Fauci said a test of that nature should be ready to go in the next few weeks.

“We’re going to have a rather large number,” he stated.

Other countries are already considering the same idea. Germany and China have implemented one form of the identification, while the United Kingdom and Italy are considering the option.

In China, some areas are requiring people to display a color code on their smartphone to show whether they’ve been exposed or at risk of infection. The monitoring was implemented on Wednesday, when the lockdown was lifted in Wuhan — the location where the virus is believed to have originated.

As Business Insider reported, an online payment app that everyone with a smartphone in China uses displays green, yellow, or red to indicate whether they can leave the house. If they can, the color coding will reveal where they are able to go.

Red means a person could have or could likely have the virus, yellow means a person has been in contact with someone who has the virus, and green means an individual is symptom-free and can travel. There are checkpoints in place at restaurants, hotels, and other public places where people must scan their phone to enter.

Effectively, the app is required now to do anything in many places. Here's what it looks like trying to get onto the subway in Hangzhou. Overnight the city went from lockdown to relying on the app. If your code is green, you can ride. If you're given yellow or red, you're stuck. pic.twitter.com/rettbnhbWW — Paul Mozur 孟建国 (@paulmozur) March 2, 2020

Although the U.S. government is considering the use of an ID card, it’s effectiveness hinges on the theory that people gain immunity from the disease after they have it. However, a recent study indicates that some people might have the disease reactivated after being declared symptom-free.