Carl Krawitt has watched his son, Rhett, now 6, fight leukemia for the past 4 1/2 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.



Rhett cannot be vaccinated, because his immune system is still rebuilding. It may be months more before his body is healthy enough to get all his immunizations. Until then, he depends on everyone around him for protection — what's known as herd immunity.



But Rhett lives in Marin County, Calif., a county with the dubious honor of having the highest rate of "personal belief exemptions" in the Bay Area and among the highest in the state. This school year, 6.45 percent of children in Marin have a personal belief exemption, which allows parents to lawfully send their children to school unvaccinated against communicable diseases like measles, polio, whooping cough and more.



Carl Krawitt has had just about enough. "It's very emotional for me," he said. "If you choose not to immunize your own child and your own child dies because they get measles, OK, that's your responsibility, that's your choice. But if your child gets sick and gets my child sick and my child dies, then ... your action has harmed my child."



Krawitt is taking action of his own. His son attends Reed Elementary in Tiburon, a school with a 7 percent personal belief exemption rate. (The statewide average is 2.5 percent). Krawitt had previously worked with the school nurse to make sure that all the children in his son's class were fully vaccinated. He said the school was very helpful and accommodating.



Now Krawitt and his wife, Jodi, have emailed the district's superintendent, requesting that the district "require immunization as a condition of attendance, with the only exception being those who cannot medically be vaccinated."



Carl Krawitt provided me with Superintendent Steven Herzog's response. Herzog didn't directly address their query, instead saying: "We are monitoring the situation closely and will take whatever actions necessary to ensure the safety of our students."