I recently had a brush with the GTScan malware. I closed the GTScan web page when it popped up onscreen and didn't download anything. There's been no sign of it since, but I'd like to be prepared if it rears its ugly head again.
McAfee is an antivirus program. Unless they are installed as part of an internet security suite, antivirus applications will usually scan for and detect viruses, but not other kinds of malware such as spyware.
Malwarebytes, meanwhile, is a highly regarded antimalware program. Installing this on your PC will provide an extra layer of security against net nasties.
Another useful antimalware tool is the free Microsoft Malicious Software Removal Tool. This will scan your computer and help you remove any infections found. The tool is also provided for free via Windows Updates.
Both tools should do a thorough job of detecting any traces of the infection and helping you to clear it up. You should also use CCleaner to delete any temporary files lurking on your system that could harbour harmful files.