Yeah, I would worry about yeast way before vaccine shedding. If you aren't comfortable buying used, but want a discount, you can go for seconds, old versions, or do prefolds. Like fuzzi bunz, bum genius, and thirsties all recently made new diapers, so if you are lucky you might find their old versions online or in a store for cheap as they try to get rid of them to make room for the newest versions. Yesterday I saw fuzzi bunz for $9 without inserts. Wish I had a credit card, those babies would have been mine. A place online called Jillian's Drawers has used that are used for 30 days or less, I believe, at a discounted price because they have a try cloth deal going on. You could always strip them, do the vinegar rinse, or I think (could be wrong, haven't done it) you can use grapfruit seed extract too, which is supposed to kill alot of things, including yeast.