Talk about a target rich environment? Any place restricting entry to VIP ticket holders will be telling the rest of us just who the problem is. I could see where walking around flashing ones VIP ticket could be a career ender. And maybe tell who has groceries? I remember back in the 50’s when designating Civil Defense shelters in public buildings and the like was a continuous thing. No restrictions on who. And we never should have stopped that program.
The bomb shelter scene in “The Dirty Dozen” comes to mind, though they wouldn’t have such ventilation set up in a doomsday shelter.