It doesn't help using anti virus when the hardware protocol itself are vulnerable. It's like pouring ketchup and salsa to the engine instead of the proper motor oil, and then taking the seat belts properly on.
Here is a couple of articles in web that may shed some light on this:
USB devices are apparently more dangerous than we’ve ever imagined. This isn’t about malware that uses the AutoPlay mechanism in Windows—this time, it’s a fundamental design flaw in USB itself.
USB drives are affordable and convenient, but that makes them attractive targets for hackers. Here’s how to avoid getting scammed by these portable storage devices.