Carl Krawitt has watched his son, Rhett, now 6, fight leukemia for the last 4½ years. For more than three of those years, Rhett has undergone round after round of chemotherapy. Last year, he finished chemotherapy, and doctors say he is in remission. Now, there’s a new threat, one that the family should not have to worry about: measles. Read more about Rhett: blogs.kqed.org/stateofhealth/2015/01/26/not-vaccinated-stay-home-from-school-says-marin-dad-of-leukemia-patient/#more-23624 Reporter: Lisa Aliferis Video: Jeremy Raff, Adam Grossberg Music: Zach Flynn