Safety and Reactogenicity of Bioconjugate Vaccine to Prevent Shigella

Inclusion Criteria: * Subjects of both sexes, aged between 18 and 50 years. * Subjects who have undergone a detailed medical history, clinical checkup and are in good health. * Subjects who have understood the purpose of the study and have freely signed the informed consent. * Subjects who consent with repeated blood samples taking. * Subjects who will be available to perform the follow-up visits, are reachable by telephone, and are able to complete the diary cards throughout the study duration. * For female volunteers, a negative pregnancy test and an adequate contraception throughout the study duration. Exclusion Criteria: * Known history of recent contact Shigella infection or long-term residence in a Shigella endemic region (Central America, Africa, and India). * Known history of hypersensitivity to any component of the vaccine (EPA; Aluminium Hydroxide). * Subjects with compromised immune system. * Family history of congenital or hereditary immunodeficiency. * Chronic administration of an immunosuppressive treatment or other immune-modifying drugs within six months prior to the first vaccine dose. * Subjects that received any other vaccine during the 1 month preceding the 1st injection and may receive before the 2nd injection. If the subject needs to be vaccinated during this period, he/she will be withdrawn from the study. * Subjects suffering of a disease at the time of enrolment. 'Disease' is defined as the presence of a mild or severe illness with or without fever. * Acute or chronic, clinically significant pulmonary, cardiovascular, hepatic or renal functional abnormality, as determined by physical examination or laboratory screening tests. * Any laboratory data collected during the screening phase found to be outside the normal range defined by the laboratory. * Positive test for HIV, and evidence of HBV or HCV. * Pregnant or breast-feeding women. * History of alcohol, drug or psychotropic drug abuse (which interferes with a normal lifestyle) during the previous year. * Subjects for which follow-up is compromised due to socio-cultural, geographic or psychological reasons. * Any other significant finding that in the opinion of the Investigator that would increase the risk of having an adverse outcome from participating in the study. * Subjects that are participating or have participated in another clinical trial in the last 6 months.