Why Background Protection is Better Than Manual Scans If you want to scan your computer with multiple antivirus programs, you’ll need to perform a manual scan with the second antivirus program instead of using its background-scanning feature. Get a Second Opinion: You should only have one antivirus program running at once, as multiple background-scanning antivirus programs can interfere with each other and cause problems with your computer.However, the virus will be caught if you try to run the file containing the virus or during a regularly scheduled full-system scan. If a virus definition has been added for that type a malware - or the antivirus’ heuristics have improved - it will only catch the dormant virus when you perform a manual scan. It’s possible that there’s a dormant virus lurking in an executable file deep on your hard drive that your antivirus missed during its first manual scan. These files basically contain a catalogue of identified malware, and your antivirus compares programs you run to the catalogue to check whether they match. Check For Dormant Malware it Missed Earlier: Antiviruses use “definition files,” which are updated regularly.However, it will still scan files for malware when you open them. After performing this scan, your antivirus can trust that your system is secure. This allows the antivirus to ensure your computer is in a clean state and that you don’t have viruses lurking in unopened files on your hard drive. When You Install an Antivirus: When you first install an antivirus, it will perform a full-system scan immediately.

Manual scans are still useful in some cases, but you don’t need to regularly open your antivirus program and initiate them: Your antivirus program doesn’t need you to click a button - it’s already doing the work. It’s also aware of all the software running on your system. In other words, you don’t need to run manual scans because your antivirus has already checked every file for malware as it arrived. This feature is generally known as background scanning, real-time protection, resident protection, on-demand scanning, or something like that

Malwarebytes manual definitions