What are COVID-19 "immunity passports?"

As the world begins to reopen after the peak of the COVID-19 pandemic, people have to consider how to do so safely in order to minimize the spread of the virus. 

One possible idea— under consideration by countries including Chile, Germany, Italy, the UK and the United States — is to have an immunity passport: a physical or digital document confirming that a person has become immune. 

Some policymakers are looking at using "immunity passports" in the context of allowing a person to return to work, school, or travel. CGTN's Ediz Tiyanşan reports.