We get over 100 faxes a day. None of these have malware. Word files can be embedded in PDFs, but again, they would have to be changed to Edit from read only.
As to A/V. Going back to Win 95, I have not seen an A/V that doesn't protect in real time. Any time a drive-by site attacks or a virus is activated or just gets on the machine, if the behavior or if a definition spots it, the A/V goes off. It doesn't wait for a scan.
Most of the high-end A/V, anti-malware programs continually go through each file and check for malware.
https://www.malwarebytes.com/premium/The other thing is a lot are adding cloud protection, meaning the agent connects to the cloud and gets all of its information from there, updates and the like. They also have central monitoring and installs, etc.
