No — and this is one of the most common false assurances in the SMB market. Traditional antivirus detects known malware signatures. Modern attackers use techniques that don't match known signatures: living-off-the-land attacks that use legitimate Windows tools, fileless malware, credential-based intrusions that never touch the disk. Antivirus misses all of these.

Endpoint Detection and Response (EDR) — what's now required by most cyber insurance carriers — uses behavioral analysis to detect anomalous activity regardless of whether it matches a known signature. It's a fundamentally different technology, not an upgrade of antivirus.