Through infected family members, Chen continued tracing the paths of infection, drawing charts of family infection routes, thereby solving the riddle of transmission. The greatest mode of infection of hepatitis B in Taiwan occurred during birth: so-called "vertical transmission" caused when the baby passes through the birth canal.
藉由病患家屬，陳定信一路往上追，畫出了一個個「家庭傳染途徑圖」，破解了傳染途徑之謎──台灣 B 肝最大感染源竟是母親分娩、胎兒經過產道時所造成的「垂直感染」。