Safety and Immunogenicity of a Vi-DT Typhoid Conjugate Vaccine

This study will be carried out in healthy adults and children at a single site. Subjects will be stratified according to age.

The study procedure is as follows:

Visit 1 (day-1 to -7): Screen participants by medical history, physical examination and lab investigations. Collect blood for safety and immunogenicity assessments.

Visit 2 (day 0): Enroll, randomize and administer first dose of vaccine to eligible participants

Visit 3 (day 3): Assess participant safety by medical history and physical examination

Visit 4 (day 7): Record solicited adverse reaction 7 days post vaccination, and collect blood for safety lab assessments.

Visit 5 (day 28): Assess participant safety, collect blood for immunogenicity assessments, and administer second vaccine dose

Visit 6 (day 31): Participants safety will be assessed by medical history and physical examination

Visit 7 (day 35): Record solicited adverse reaction 7 days post second vaccination.

Visit 8 (day 56): Collect blood for immunogenicity assessments, assess participant safety, and fill in study completion form in the absence of any safety concern.

This study is observer-blind: vaccine administrator and vaccine safety evaluator will be two distinct persons to avoid bias of safety assessment. Trial staff other than the vaccine administrator.

Inclusion criteria

• Healthy male and female individual 2-45 years of age
• Participants/Parents who have voluntarily given informed consent and/or assent.
• Participants/Parents willing to commit complying with the study procedures of the investigator and available for the entire duration of study

Exclusion criteria

• Participants concomitantly enrolled or scheduled to be enrolled in another trial
• Acute illness, in particular infectious diseases or fever (axillary temperature > 38°C), with in three days prior to enrollment and vaccination.
• Known history of allergy to vaccines or other medications
• Known history of allergy to egg, chiken protein, neomycin and formaldehyde.
• History of uncontrolled coagulopathy or blood disorders
• Known history of immune function disorders including immunodeficiency diseases, or chronic use of systemic steroids (> 20 mg/day prednisone equivalent for periods exceeding 10 days), cytotoxic or other immunosuppressive drugs
• Any abnormality or chronic disease which in the opinion of the investigator might be detrimental for the safety of the participant and interfere with the assessment of the trial objectives
• Pregnancy & Lactation (female adults)
• Female with child-bearing potential during the study period. i.e., sexually active and not practicing effective acceptable contraceptive method
• Individuals who have previously received any vaccines against typhoid fever
• Individuals already immunized with any licensed vaccine within 4 weeks prior to enrolment/vaccination (day 0) and expected to receive other licensed vaccines within 60 days following the first dose (day 0), except for tetanus toxoid vaccine
• Individuals who have a previously ascertained or suspected disease caused by S. typhi.
• Individuals who have had household contact with/and or intimate exposure to an individual with laboratory-confirmed S. typhi
• History of alcohol or substance abuse
• Subject planning to move from the study area before the end of study period