Jumping the gun a bit, aren't they ?
The UK contact tracing app has just been made available and scammers are already on the hunt ?
It's a bit quick I think, and a lot of those calls must logically end in "but I don't have the app on my phone yet, so how did I get into your database ?".
Of course, there still is the obvious issue of users not engaging brains when getting a phone call, so maybe it's okay for the scammers.