I came across this in a daily devotion and didn’t remember seeing the word infected in any other translation. But the NLT does make sense. If you are infected with a disease you need a cure. God has the cure, but we keep turning away.
Isaiah 64:6-7 (NLT2) We are all infected and impure with sin. When we display our righteous deeds, they are nothing but filthy rags. Like autumn leaves, we wither and fall, and our sins sweep us away like the wind. Yet no one calls on your name or pleads with you for mercy. Therefore, you have turned away from us and turned us over to our sins.