It 'true that the Mac does not need antivirus and spam?

The Mac operating system, like all Unix operating systems, are not plagued by security breaches and virus problem that is present on Windows. The structure is very solid as Unix to make changes at the system level is necessary to know the administrator password, the things that was not necessary on Windows computers. So I'm saying that if you use a Mac you will not need to install antivirus software that will slow down the operating system exclusively. However the virus is always better to be the common sense when using the computer.