The VRDB isn't a backup and it doesn't copy complete files only certain information to be able to try and repair the file. I also doesn't scan all your files, commonly this is exe files that are the main target for true virus infection.
C:\Program Files\Alwil Software\Avast4\DATA\integ\avast.int is where that data is collated, you would have trouble trying to delete it anyway as the self-defence module would stop you, unless you disabled it.