COVID 19 has pretty much shut the country down but, this idea could allow more to go about their business normally.

Businesses are closed or operating in a limited capacity while we're all under orders to stay home. Some people may be resistant to the virus though and those people may eventually be able to get "immunity certificates" or "COVID Passports" allowing them to move about freely.

According to boston.com:

People who survived severe acute respiratory syndrome (SARS) in 2003, which was caused by a closely related coronavirus, had antibodies to it for at least several years.

SARS and COVID 19 are similar, hence the comparison. Allowing those with the proper immunities to get back to work would be the first step toward everyone getting back to normal but there are many questions about the tests' reliability.

No one knows whether infection with SARS-CoV-2 confers immunity to reinfection and, if it does, how strong that immunity is and for how long it lasts. Not only is that information missing, but we cannot get it soon — it will be nine months before we can know if antibodies last a year. - boston.com

Who knows what will come of this but, it's a glimmer of hope for a return to normalcy.