https://astralcodexten.substack.com/p/book-review-from-oversight-to-overkill
Dr. Rob Knight studies how skin bacteria jump from person to person. In one 2009 study, meant to simulate human contact, he used a Q-tip to cotton swab first one subject’s mouth (or skin), then another’s, to see how many bacteria traveled over. On the consent forms, he said risks were near zero - it was the equivalent of kissing another person’s hand.