Hi Commanderqa
I have been a virus expert for many years. Mac don't get viruses unless they are jailbroken and exposing its security features to a certain degree where infiltrators (for example someone is calling your home phone and say they are from Apple) can do harm to your operating system (OSX) of your mac computer.
Personally I have removed malwares but not viruses on both macbooks and ipads. Malwares are not viruses. Some of them are annoying applications that tend to cover the entire screen or give you the feeling that your computer is slow or that it is infected with X amount of viruses. They are 100% fake and fraudulent. In the end the folks behind them are expecting your credit card or some method of payment that will allow them to take and run away with it. Malwares are treatable manually and some of them require special softwares such as AdwareMedic which was currently aquired by MalwareBytes since it was a very efficient tool of removing mac malwares.
Adding an antimalware or antivirus will depend of how often you go to websites and download attachments and more importantly on what you click on.
Personally i do not recommend in having an antivirus installed to protect you but have its dmg downloaded in case you may need to install it when you want to scan and remove such malware.
The 3 main malicious categories that affect computers these days are viruses, malwares, and spywares.
On Macs I have encountered malwares only in all my years of experience with them.