Parents who send their children to private schools in California are much more likely to opt out of immunizations than their public school counterparts, an Associated Press analysis has found, and not even the recent re-emergence of whooping cough has halted the downward trajectory of vaccinations among these students. The state surveys all schools with at least 10 kindergartners to determine how many have all the recommended immunizations. The AP analyzed that data and found the percentage of children in private schools who forego some or all vaccinations is more than two times greater than in public schools. More troubling to public health officials is that the rate of children entering private schools without all of their shots jumped by 10 percent last year, while the opt-out figures held steady in public schools for the first time since 2004. Public health officials believe that an immunization rate of at least 90 percent in all communities, including schools, is critical to minimizing the potential for a disease outbreak. About 15 percent of the 1,650 private schools surveyed by the state failed to reach that threshold, compared with 5 percent of public schools…