BOSTON, May 19, 2014 /PRNewswire/ -- Sanofi Pasteur, the vaccines division of Sanofi (EURONEXT: SAN and NYSE: SNY), presented Phase II trial (H-030-012) results for an investigational vaccine for the prevention of Clostridium difficile (C. diff) infection (CDI) at the 114th General Meeting of the American Society for Microbiology (ASM). The Phase II trial met its primary objectives, reactions were generally mild and of short duration, and the candidate vaccine generated an immune response against C. diff toxins A and B. These toxins are largely responsible for CDI, which can cause potentially life-threatening gut inflammation and diarrhea. Based on the Phase II results, a high-dose plus adjuvant vaccine formulation administered on days 0, 7 and 30 was selected for further evaluation in the global efficacy program, Cdiffense. This ongoing Phase III trial began in August 2013 with plans to include up to 200 sites in 17 countries. " C. diff infection threatens the many people who frequently use antibiotics, as well as older hospitalized patients and residents in long-term healthcare facilities," said Jamshid Saleh, M.D., who participated in Phase II and is currently the principal investigator for the Phase III trial at Northern California Clinical Research Center in Redding, California. " It would be great if we could offer patients a way to help prevent this contagious and debilitating disease versus just treating it after it happens." The Phase II vaccine study was a randomized, multi-center trial split into two stages. The first, conducted with 455 volunteers, was placebo-controlled, double-blind and designed for dose and formulation selection. The second, which included 206 additional volunteers, was designed to compare the dose and formulation chosen in the first stage against two alternate dosing schedules. Volunteers in the study were adults aged 40-75 years who were at risk of CDI due to impending hospitalization or residence in a long-term healthcare facility.