If your external drive has not been infected, you can enable Drive Security Antivirus so every file copied from your computer into the drive will be scanned for viruses and not copied (or backed up). As a result, viruses will not be copied to a drive and subsequently to your cloud folder. You can keep your USBtoCloud drive and your backup completely virus free. To enable DriveSecurity™ select the Antivirus option in the Settings menu.