Does one need an antivirus program on a Mac? This question, and answers, have appeared many times in the past.
Here is an article with yet another review of this question. Short answer: no. But if it makes you feel more comfortable running an AV program on your Mac, as I do, I see no downside in doing so. Maybe one day the AV program will stop a virus from infecting my Mac. Even if this never occurs, great. Hasn't cost me anything for the additional piece of mind.
Following is the article, should you have an interest in the author's comments and opinions.