Most all of them miss something from time to time. Paid or free versions,None are 100% I use Avast free on our tower pc and the microsoft Defender on both of our laptops. About every 2-3 months I run the Microsoft Safety scanner and a Malwarebytes scan and on occasion a Superantispyware scan. All free, Download them ,run them as needed and remove them. Those 3 will catch anything the Avast or defender or whatever antivirus might miss. The most common thing they catch is "PUPs" and "tracking cookies" Our daughter has used Kapersky on her laptop through 4 years of college with no issues. Nothing wrong with Kapersky at all, but like any other it is not a bad idea to occasionally do a scan with MAlwarebytes or Microsoft Safety scanner. Use Kapersky and rest easy.