For your possible interest, Kaspersky has just announced a free version of their antivirus program. Comments from Eugene Kaspersky can be read here. If you want to try it, the free download is here. It is available for both a PC and Mac.
I've downloaded it, but haven't installed it yet, but probably will soon. Over the years Kaspersky has gotten good reviews as being an effective AV program. For example, read here. And you've probably read recently about whether Kaspersky could be spying for Russia. Eugene, of course, soundly denies this allegation and has offered to make his program code available for review.
Being on the curious side I'll give Kaspersky AV a try for both my Mac and PC. Will be interesting to see what I think about it. Presently I run both Avast AV and Avira AV, and have been pleased with both. I do get a popup ad occasionally wanting me to upgrade to their paid version. Can't blame them for that.