Short answer: no. There are many free and very effective antivirus solutions for your devices, no matter what operating system you use. (see links below)
However, there are some caveats to that answer. If you have household members or office staff that are known to have fearless or even careless browsing habits, you may want to consider protecting your devices with more robust defences. The full internet security suites have additional safety features that may better protect your devices from a wider array of threats. It is also advised to educate your users on safe computing habits, because even the best internet security is not foolproof. Netsafe is an excellent resource to learn more about internet safety.
If your broadband provider is Spark, as a fantastic benefit for their customers, you are able to install the McAfee Internet Security Suite (worth $95/license year) on up to 5 devices. Click here for more information.
Welly IT Solutions can recommend the following free antivirus solutions:
Avast (MacOS, Windows, Android)
AVG for PCs (Windows)
AVG for Mac: Download