With today’s technologies, something like a vaccine passport can easily morph into a surveillance and compliance tool for various levels of government. From Victoria Taft at pjmedia.com:

The Left would like to dismiss Naomi Wolf as a heretic and conspiracy theorist now that she disagrees with their anti-liberty responses to coronavirus, but her warning about President Biden’s threatened “vaccine passports” should be heeded.
Here’s what she means, in case you haven’t figure it out yourself.
Vaccine passports sound like a fine thing if you don’t know what those platforms can do. I’m CEO of a tech company, I understand what this platform does. It’s not about the vaccine, it’s not about the virus, it’s about data. And once this rolls out you don’t have a choice about being part of the system. What people have to understand is that any other functionality can be loaded onto that platform with no problem at all.
Wolf told Fox News host Steve Hilton that Big Tech companies will oversee all of your personal information and intermingle it with information that government will use to determine if you’re eligible to be able to travel and do anything else in polite society. President Biden signed an executive order in January to coordinate with other countries to track people to stop the spread of COVID.