Well ... we are recommended to only use one AV at any time. So, if the chosen AV misses the infection, how do we find out ... assuming that a product like Malwarebytes (manual testing) does not highlight an infection.
To add ... I switched from another AV to Avast and am pleased with my choice.
Well, firstly if it was missed, then it will likely be picked up later by the updated database.
Second, you can always run online scans at one of the AV vendors.
Many of the better companies have online systems to scan your machine, especially useful if your installed system is compromised at any time.
Herd Protect is a useful tool, that can be installed as it runs in the cloud, it checks your systems against 60+ antivirus/malware systems. Occasional checks with that should pick up most things.
And there is also the virus forum here, if you suspect something is wrong the experts can check your system for you.