First what choice did you make when they were detected move to chest, move/rename or delete, etc. ?
What version of avast do you have home or pro ?
The reason I ask is to have 226 infected files the home version normally requires interactive action only the pro version can do an uninterrupted scan and present the results at the 'end' of the scan.
If you moved them to the chest, they are safe there, there is no rush to delete anything from the chest, a protected area where it can do no harm. Anything that you send to the chest you should leave there for a few weeks. If after that time you have suffered no adverse effects from moving these to the chest, scan them again (inside the chest) and if they are still detected as viruses, delete them.
Are you sure that they were reported as infected or simply that avast 'couldn't' scan them ?