Recently, we released the only official Windows-specific version of ClamAV for Windows. It uses an advanced cloud-based protection mechanism, best of all it’s free (as in free beer) If you haven’t tried it yet, I really encourage you to. If you have a 64-bit Windows operating system, you will get a speed boost from running the 64.bit version. The more people that run ClamAv for Windows, the better the protection. Every time a user encounters a new threat, all other users are protected from that same threat in real-time.”]
Source: https://blog.talosintelligence.com/2010/06/clamav-for-windows.html