Testing a new Shigella vaccine with an adjuvant in healthy adults

Inclusion Criteria:

1. Healthy adult, male or female, aged 18 to 50 years (inclusive) at the time of inclusion (=vaccination).
2. Provide written informed consent before initiation of any study procedures.
3. Available to complete all study visits and procedures.
4. Negative stool PCR test for Shigella.
5. Women of childbearing potential: negative pregnancy test at screening and before each study vaccine administration. Women are considered not of childbearing potential if they are postmenopausal (no menses for 12 months without an alternative medical cause), or if they have no uterus or no ovaries. Women of childbearing potential must agree to use continuous adequate contraception to avoid pregnancy during the study, for at least 4 weeks before the first vaccination and for 3 months following the last vaccine dose.

Adequate methods of contraception for this study include:

1\. hormonal contraception

1. combined (estrogen and progestogen containing) hormonal contraception associated with inhibition of ovulation (oral, intravaginal, or transdermal)
2. progestogen-only hormonal contraception associated with inhibition of ovulation (oral, injectable, or implantable) 2. intrauterine device (IUD) 3. intrauterine hormone-releasing system (IUS) 4. bilateral tubal occlusion/litigation procedure 5. vasectomized partner (the vasectomized partner should be the sole male sexual partner for that participant).

   6\. sexual abstinence (defined as refraining from heterosexual intercourse from signing the informed consent until 3 months after the last vaccine dose).
   1. Any history or evidence of clinically relevant chronic medical conditions (such as: psychiatric conditions, diabetes mellitus, hypertension \[treated by medication\], autoimmune disorders, immunodeficiencies, cardiovascular, renal disease or inflammatory bowel disease). Trial physicians (in consultation with the principal investigator) will use clinical judgement on a case-by-case basis to assess safety risks under this criterion.
   2. Current use of immunosuppressive medications (except for antihistamines and topical or inhalation corticosteroids).
   3. Women who are a) currently nursing or b) who are pregnant or planning to become pregnant during the study period plus 3 months beyond the last vaccine dose.
   4. Participation in research involving another investigational product (defined as receipt of an investigational product or exposure to an invasive investigational device) 30 days before the first vaccination or anytime through the last in-clinic study safety visit.
   5. Positive blood test for hepatitis B surface antigen (HbsAg), hepatitis C virus (HCV), or human immunodeficiency virus (HIV).
   6. Clinically significant abnormalities on basic laboratory screening tests.
   7. Systemic antimicrobial treatment (i.e., topical treatments are not an exclusion criterion) within 1 week before the first vaccine dose (temporary exclusion).
   8. Known hypersensitivity to compounds in the vaccine or adjuvant or other known drug allergies that may increase the risk of adverse events.
   9. Regular use (weekly or more often) of antidiarrheal, anti-constipation, or antacid therapy.
   10. Abnormal stool pattern (fewer than 3 stools per week or more than 3 stools per day) on a regular basis; loose or liquid stools on other than an occasional basis.
   11. Personal or family history of inflammatory arthritis.
   12. Proven allergy to any substance in the InvaplexAR-Detox vaccine or dmLT or history of anaphylactic reaction to any other vaccine.
   13. Exclusionary skin disease history/findings that would confound assessment or prevent appropriate monitoring of local AEs, or possibly increase the risk of local AEs.
   14. Recent (\<3 months) history of gastroenteritis.
   15. Received previous licensed or experimental Shigella vaccine, dmLT or live Shigella challenge.
   16. Any severe medical condition that might place the participant at increased risk of adverse events according to the clinical judgment of the study clinicians in consultation with the PI.
   17. Any planned vaccination within 14 days before the first vaccine dose until the last in-clinic study visit, with the exception of SARS-CoV-2 vaccines or influenza vaccines.