Pneumococcal diseases, caused by the bacterium Streptococcus pneumoniae, include pneumonia and otitis media, which accounts for some 12 million doctor visits per year in the United States alone. Each year around the world, pneumococcus causes 1.2 million deaths due to pneumonia, 39% of which are in children under the age of five. In a three-year Phase III clinical trial involving 38,000 children, in which half of the infants received a new pneumococcal vaccine and half received a placebo vaccine, the new vaccine demonstrated an efficacy rate of 100% against bacterial meningitis and bacteremia, the two most deadly pneumococcal afflictions.