No protection software is perfect.
My friend has Norton he think his system is immune to viruses.
He try Avast it detects 3 malwares that norton didnt detect it.
My point here is No one is perfect.
If you want really your system runs safe try sandboxie.
I dunno if norton has sandbox.
Trust me sandbox now is getting popularity.
Mostly new AV now using sandbox as additional for their protection.
Actually using free Anti-virus Software is my good choice.
Try this one
Avast = Free
Malwarebytes = Free
Sandboxie = Paid