I know, another person with another infection question. It's a pliny clone been in primary for 10 days, just opened to take a first gravity reading, hit target gravity. Is this an infection, or leftover krausen/yeast?
Not sure what you mean by "dropping" an infection. You're not going to remove a biologically active entity just by chilling its ass
Assuming you take a couple of successive SG readings and have convinced yourself the yeast are done cleaning up after themselves, a solid crash will drop a heck of a lot of debris. But it's not going to kill an infection.
Fortunately, I don't think you're looking at an infection. Yet...