QVDs are files which are stored into a filesystem managed by Windows OS. You can store QVDs in different folders and apply permissions over those folders so only allowed developers can even read from that folder, i.e.: Development folder only allows Read and Modify to those in the Active Directory security group Developers.
It must be this way, because files are handled by the operating system.
You can use section access to prevent users to read from QVW files, but while a QVW file is the app itself with al design, data, script, security, etc. the QVD file is just table storage.