Yet another panel of scientists has found no evidence that a popular vaccine causes autism. But despite the scientists’ best efforts, their report is unlikely to have any impact on the frustrating debate about the safety of these crucial medicines. “The M.M.R. vaccine doesn’t cause autism, and the evidence is overwhelming that it doesn’t,†Dr. Ellen Wright Clayton, the chairwoman ... --snip-- The panel did conclude, however, that there are risks to getting the chickenpox vaccine that can arise years after vaccination. People who have had the vaccine can develop pneumonia, meningitis or hepatitis years later if the virus used...