A study to evaluate safety and immunogenicity of 1 booster dose of 1790GAHB vaccine in healthy adults primed with 3 doses of 1790GAHB vaccine in study H03_01TP compared to 1 vaccination of 1790GAHB in either subjects who received placebo in the same study or naïve subjects not part of H03_01TP study

Males and females, aged 22 to 50 years, who were previously vaccinated, with either vaccine (3 doses) or placebo, in H03_01TP and who had undetectable antibody titers at baseline, or Males and females, aged 22 to 50 years, who were not part of H03_01TP.

• Individuals who, after the nature of the study has been explained to them, and prior to any protocol specific procedures being performed, have given written consent according to local regulatory requirements.
• Individuals in good health as determined by the outcome of medical history, physical examination, hematological blood tests and clinical judgment of the investigator.
• If women of child-bearing potential, have a negative urinary pregnancy test prior study vaccination and willingness to use acceptable birth control measures for the entire study duration.
• Individuals affiliated to a social security regimen.

Individuals with behavioral or cognitive impairment or psychiatric disease that, in the opinion of the investigator, may interfere with the subject's ability to participate in the study.

• Individuals with any progressive or severe neurological disorder, seizure disorder or Guillain-Barré syndrome.
• Individuals who are not able to understand and to follow all required study procedures for the whole period of the study.
• Individuals with known hepatitis B or C or suspected HIV infection or HIV related disease with history of an autoimmune disorder or any other known or suspected impairment /alteration of the immune system.
• Progressive, unstable or uncontrolled clinical conditions.
• Hypersensitivity, including allergy, to any component of vaccines, medicinal products or medical equipment whose use is foreseen in this study.
• Individuals with a known bleeding diathesis, or any condition that may be associated with a prolonged bleeding time.
• Clinical conditions representing a contraindication to intramuscular vaccination and blood draws.
• Abnormal function of the immune system resulting from:

Systemic administration of corticosteroids for more than 14 consecutive days within 90 days prior to informed consent;

• Administration of antineoplastic and immunomodulating agents or radiotherapy within 90 days prior to informed consent.
• Received immunoglobulins or any blood products within 180 days prior to informed consent.
• Study personnel as an immediate family or household member.
• Any other clinical condition that, in the opinion of the investigator, might interfere with the results of the study or pose additional risk to the subject due to participation in the study.
• Individuals who have received an investigational product in another clinical trial 28 days prior to first study visit or intent to receive another investigational product at any time during the conduct of this study.
• Individuals who received any other vaccines within 4 weeks prior to enrollment in this study or who are planning to receive any vaccine within the entire study duration. Inactivated influenza vaccine can be given, but only 4 weeks earlier or 4 weeks later than the date of immunization.
• Individuals who have received blood, blood products, and/or plasma derivatives including parenteral immunoglobulin preparations in the past 180 days.
• Individuals with body temperature > 38.0 degrees Celsius within 3 days of intended study vaccination.
• Individuals with Body Mass Index > 30 kg/m2.
• Individuals with history of substance or alcohol abuse within the past 2 years.
• Women who are pregnant or are breast-feeding, or are of childbearing age who have not used or do not plan to use acceptable birth control measures, for the duration of the study.
• Females with history of stillbirth, neonatal loss, or previous infant with anomaly.
• Individuals who have a previously laboratory confirmed or suspected disease caused by S. sonnei.
• Individuals who have had household contact with/and or intimate exposure to an individual with laboratory confirmed S. sonnei.
• Any condition, which, in the opinion of the investigator may pose an increased and unreasonable safety risk to the subject if participating to the present study.
• Individuals with a neutrophil count value lower than 1.8 10^9/L at screening assessment.
• Individuals with human leukocyte antigen (HLA)-B27 positive and/or with history of reactive arthritis.
• Previous history of Benign Ethnic Neutropenia or drug related Neutropenia and/or concomitant treatment with neutropenic agents.