I am a veterinary technician and will say we see more socialized, fearful and/or dog aggressive dogs than parvo cases. The disease is certainly a risk but in my opinion, keeping your puppy secluded during a time they are most accepting and willing to learn is worse.
Places to avoid are parks (dog and regular), pet stores, the floor of vet offices and other places dogs are going in and out of. Parvo can survive in grass, unable to be sterilized like tile in stores and hospitals. I carried my puppy around the first few weeks. Then we visited less dog populated places like Starbuck's, Home Depot, sitting on blanket on a main street, watching people walk by.
Puppy classes and training are good outlets for meeting other dogs. They usually require vaccinations for all the pups attending. Do not consider any place letting in puppies without their first distemper/parvo.
♥ Faun GSD 12-22-13
♥ Daisy Rat Terrier/Beagle Mix 3/15/02