The first experimental vaccine designed to prevent a common and often deadly group of early childhood infections has proved highly effective and may also reduce the number of troublesome ear infections in preschoolers, according to researchers. The vaccine prevents "invasive" pneumococcal diseases, including life-threatening bacterial meningitis, blood poisoning and pneumonia. Henry Shinefield is the co-director of the vaccine study center for Kaiser Permanente in Oakland, California, that conducted the study.