Brigham Research Institute (BRI) - Brigham and Women's Hospital

1. Healthy adults aged from 18 to 55 years old. 2. Considered healthy, as judged by the clinical investigator, according to medical history, physical examination, vital signs, screening laboratories, and medication history. 3. Understanding and agreeing to comply with the study protocol including the inpatient period. 4. Female participants must be non-pregnant and non-lactating and either 1. surgically sterile (history of bilateral ligation, bilateral salpingectomy, bilateral oophorectomy, total hysterectomy) or postmenopausal (defined as as amenorrhea for at least 12 consecutive months before screening without an alternative medical cause) 2. be of child-bearing potential and practicing an acceptable method of contraception or abstaining from all activities that could result in pregnancy for at least 28 days before vaccination until 3 months after receiving the IP. Acceptable methods of contraception include barrier methods (such as condom, diaphragm, or cervical cap used in conjunction with spermicide), intrauterine device, hormonal contraception (that may be taken or administered by oral, intravaginal, transdermal, subdermal or IM route), vasectomized partner (the vasectomized partner should be the sole partner for that participant).

Each participant must not meet any of the following exclusion criteria to be eligible for enrollment in the study: 1. Confirmed or suspected immunosuppressive condition, as a result of a disease (e.g., primary immune deficiency, malignancy, HIV infection) or have taken any systemic immunosuppressive therapy within 6 months of enrollment. 2. Pregnant or lactating women 3. History of gastrointestinal (GI) disorder, such as previous major GI surgery, malabsorption, or any chronic GI disorders that would interfere, according to the investigator, with the IP. 4. Acute GI or febrile illness within 7 days of enrollment. 5. Have any acute or chronic medical condition that, in the opinion of the investigator, would make vaccination unsafe or interfere with the evaluation of immune response to study vaccination. 6. History of cholera vaccination 7. History of cholera infection 8. Abnormal stool pattern, defined as < 3 or >21 stools per week. 9. Allergy or intolerance to PanChol or placebo component (sodium bicarbonate, lactose, ascorbic acid) 10. Use of any systemic antibiotics within 1 month of PanChol administration 11. Receipt of a live vaccine in the previous 4 weeks or planned in the 4 weeks following enrollment 12. Receipt of a killed or subunit (non-live) vaccine in the previous 2 weeks or planned in the 2 weeks following enrollment. 13. Individuals who do not speak English will not be enrolled into this trial. This study involves more than minimal risk and no prospect of direct benefit for participants. Additionally, a subject who did not speak English may not be able to easily communicate safety concerns in a timely fashion to the study investigators 14. Childcare workers with direct contact with children ≤ 2 years of age 15. Individuals whose occupation involves handling of food 16. Healthcare workers who have direct contact with patients who are immunodeficient, HIV-positive, or have an unstable medical condition 17. Use laxatives regularly 18. Have diarrhea within 48 hours before enrollment 19. Have a history of hypersensitivity to any of the tetracyclines 20. Have a history of hypersensitivity to streptomycin or any aminoglycoside due to the known cross-sensitivity of patients to drugs in this class.