It’s a clear gel that battles the common cold, but it isn’t hand sanitizer. Instead, Swype Shield, billed as physician-invented cold and flu prevention product, is applied on the nostrils, which is where cold and flu viruses most often enter the body.  The firm behind the product, Nuance Health, LLC, contends the formulation killed more than 99% of 25 cold and flu viruses in lab testing. The active ingredients in Swype Shield are non-toxic and safe to apply to the skin multiple times a day. And...