Efficacy Study of IM Administered CssBA+dmLT Against Moderate-severe Diarrhea in Human Infection Model With ETEC Strain B7A in Healthy Adults

Inclusion criteria

• ✓. Non-pregnant, non-breast-feeding adults, age 18 to 49 years (inclusive) at the time of enrollment.
• ✓. Willing and able to sign and date informed consent document prior to study procedures.
• ✓. Stated willingness to be available for all study visits and comply with all trial procedures throughout the duration of the trial, including adherence to Lifestyle Considerations.
• ✓. Participants of childbearing potential must have a negative pregnancy test at study enrollment.
• ✓. For participants of childbearing potential\*: agree to use highly effective contraception with heterosexual intercourse for at least 1 month prior to the first vaccination through at least two months after receipt of the challenge agent or last dose of study product if not challenged. True abstinence is also acceptable.
• ✓. Body mass index (BMI) 19 to less than 40 kg/m\^2 at screening.
• ✓. In good health. As determined by medical history and physical examination to evaluate acute or ongoing chronic medical diagnoses/conditions that have been present for at least 90 days, which would affect the assessment of safety of participants and interpretations of the scientific aims of the trial. Chronic medical diagnoses/conditions should be stable for the last 60 days (no hospitalizations, ER, or urgent care for condition or need for supplemental oxygen). This includes no change in chronic prescription medication, dose, or frequency as a result of deterioration of the chronic medical diagnosis/condition in the 60 days before enrollment. Any prescription change that is due to change of health care provider, insurance company, etc., or done for financial reasons, and in the same class of medication, will not be considered a deviation of this inclusion criterion. Any change in prescription medication due to improvement of a disease outcome, as determined by the Principal or sub-Investigator licensed to make medical diagnosis, will not be considered a deviation of this inclusion criterion. Participants may be on chronic or as needed (prn) medications if, in the opinion of the participating site PI 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/condition. Similarly, medication changes subsequent to enrollment and trial vaccination are acceptable provided the change was not precipitated by deterioration in the chronic medical condition, and there is no anticipated additional risk to the participant or interference with the evaluation of responses to trial vaccination.