[Stephen]

From Samsung.com

Samsung Knox can protect your devices against viruses although it is not an antivirus software in its own right. Samsung Knox isn't a program or application, but is hardware built into your Samsung device at the point of manufacture.

From androidpolice.com

Samsung Knox's security features are so robust that, despite not being antivirus software, it can protect your Samsung phones against viruses and malware. Samsung Knox's security and Android's security features protect your phone's data against viruses and other foreign threats.