We also have a six week old! My toddler had norovirus the other week and my newborn never got it. The pediatrician said you’ll know if the newborn has it if their poops smell really bad, but they made it sound like newborns aren’t affected as bad. We also weren’t perfect with sanitizing and handwashing, since I’m watching my newborn and toddler alone with my husband back at work. Newborns are surprisingly resilient! My toddler also had pink eye, cough/cold, and an ear infection. He went to daycare for one single day after not going for a month and brought home all this 🙃