A Study to Determine If a New Shigella Vaccine is Safe, Induces Immunity and The Best Dose Among Kenyan Infants

Inclusion Criteria: All ages * Healthy by medical history, laboratory findings and physical examination before entering into the study (Participants with a minor illness (such as mild diarrhoea, mild upper respiratory infection) without fever may be enrolled at the discretion of the investigator) * Seronegative for HIV, hepatitis B and C (as per screening laboratory tests) * Resident in the study area village during the whole trial period (Kilifi -Kilifi Health and Demographic Surveillance System (Described in more detail in the SSA); (Kericho-a 75km radius from the Kericho Clinical Research Centre). * Previously completed routine primary vaccinations (6,10 and 14 weeks or thereabouts) to the best knowledge of the participant/parent/guardian. * Signed/thumb written informed consent, in accordance with local practice, provided by adult volunteers (participants 18 years of age and older), parents or legal representatives for children and infants participants as applicable, who, in the opinion of the investigator, can and will comply with the requirements of the protocol * Demonstrated comprehension of the protocol procedures by passing score of 90% or better on a written/verbal comprehension test. Adults * Female and male participants between, and including 18-50 years at the time of first vaccination * Female participants of non-childbearing potential may be enrolled in the study. Non-childbearing potential is defined as pre-menarche, current bilateral tubal ligation or occlusion, hysterectomy, bilateral ovariectomy or post-menopause. Female volunteers of childbearing potential may be enrolled in the study if the participant: has a negative urine pregnancy test at the day of screening and vaccinations, respectively, and * agree to use effective contraception for 30 days prior to vaccination and * agree to continue contraception at least for 2 months after completion of vaccination series. Children and Infants * Female and male aged 9 months (+/- 1 month) old (infants) or between, and including, 2-5 years of age (children) at the time of the first vaccination * Born full-term (i.e. after a gestation period of 37 to less than 42 completed weeks) Exclusion Criteria: All ages * Any clinically significant deviation from the normal range in biochemistry or haematological blood tests. * Suspected or known hypersensitivity (including allergy) to any of the vaccine components or to previous vaccine, or to medicinal products or medical equipment whose use is foreseen in this study * Clinical conditions representing a contraindication to intramuscular vaccination and blood draws * Any confirmed or suspected immunosuppressive or immune-deficient condition. * Systemic administration of corticosteroids (PO/IV/IM): prednisone ≥20 mg/day, or equivalent for more than 14 consecutive days from birth (for infants) / within 90 days prior to informed consent. Inhaled except for doses \> 800 mg/day and topical steroids are allowed. * Administration of antineoplastic or radiotherapy from birth / within 90 days prior to informed consent. Participants may be on chronic or as needed medications if, in the opinion of the site principal investigator or appropriate sub-investigator, they pose no additional risk to participant safety or assessment of reactogenicity and immunogenicity and do not indicate a worsening of medical diagnosis or condition * Known exposure to Shigella during lifetime of the subject * Concurrently participating in another clinical study, or participation in the preceding month, at any time during the study period, in which the participant has been or will be exposed to an investigational or a non-investigational vaccine/product (pharmaceutical product or device) * Acute disease and /or fever at the time of enrolment Note: enrolment may be postponed/delayed until such transient circumstances have terminated * History of any malignancy of lymphoproliferative disorder * Known to be part of study personnel or being a close family member to the personnel conducting this study. * Previous history of significant persistent neutropenia, or drug related Neutropenia * Adults with clinical wasting; children with weight-for-age Z score less than -3SD. * History of any chronic or progressive disease (e.g., neoplasm, insulin dependent diabetes, cardiac, renal or hepatic disease) that according to judgment of the investigator could interfere with the study outcomes or pose a threat to the participant's health * History of surgical splenectomy or Sickle cell disease (SCD test performed at KEMRI-CGMRC only). * Administration of immunoglobulin and/or any blood products within the three months preceding the first dose of study vaccine * Any medical, social condition, or occupational reason that, in the judgment of the investigator, is a contraindication to protocol participation or impairs the volunteer's/parent's/guardian's ability to give informed consent, increases the risk to the potential participant because of participation in the study, affect the ability of the volunteer to participate in the study or impair interpretation of the study data . Adults * Women who are breastfeeding * History of chronic alcohol consumption and/or drug abuse. Chronic alcohol consumption is defined as: a prolonged period of frequent, heavy alcohol use; the inability to control drinking once it has begun; physical dependence manifested by withdrawal symptoms when the individual stops using alcohol; tolerance, or the need to use more and more alcohol to achieve the same effects; a variety of social and/or legal problems arising from alcohol use.