Nevada County has the lowest rates for childhood immunization in the state of California, making the entire region vulnerable to potentially severe outbreaks of infectious disease, health officials said Tuesday. “A community with a low vaccination rate is susceptible to outbreaks,” said Dr. Karen Milman, the director of the Nevada County Health Department. “Immunizations are not only about protecting the individual child but also the child next to them.” For the school year 2011-12, 760 kindergarten-aged children enrolled in Nevada County schools, of which 544 (72 percent) were fully up to date on all immunizations, according to results tabulated and …