Few days ago my wife PC got infected with AVAST running. All her files were crypeted by the malware/virus Ransomware and now the the attacker generated txt file asking for $500 viat bitcoin. The PC is compromised now as there is no solution for the problem. AVAST is shame for this reason alone. We’re talking about year 2016 Avast Internet Security updated every single time.
There isnt an anti virus that exists that can detect and block 100% of all infections. If you were hit with a day zero infection chances are no anti virus out there that would have detected it.
The only way to block 100% of infections is to never connect to the internet.