This is a trial to evaluate the safety, reactogenicity, immunogenicity and efficacy of a 10\^6 cfu dose of an oral live-attenuated S. sonnei vaccine candidate, WRSs2, in up to 120 healthy males and non-pregnant females aged 18-49, inclusive. This is a two-phase study, an outpatient WRSs2 vaccination phase and an inpatient S. sonnei 53G challenge phase. After the initiation of the study, two participants had Grade 3 diarrhea and/or vomiting in the days following vaccination. The vaccination dose was reduced to 5X10\^5, enrollment was changed to 2 arms and randomized 2:1 (vaccine: placebo). Participants with morbid obesity were excluded and weight loss medications prohibited. The Primary Objective of this study is to estimate combined vaccine efficacy of 2 doses of WRSs2 (10\^6 cfu or 5X10\^5 cfu) in preventing shigellosis, following challenge with S. sonnei strain 53G.
Who can participate
Age range
18 Years – 49 Years
Sex
ALL
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AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
Inclusion criteria
. Provide informed consent prior to initiation of any study procedures.
. Are able to understand and comply with planned study procedures and be available for all study visits.
. Is 18-49 years of age inclusive and in sufficiently good health\* to be safely enrolled in this study as determined by medical history, medication use, and abbreviated physical exam.
Exclusion criteria
. Oral temperature is less than 100.4 degrees Fahrenheit.
. Pulse is 50 to 100 beats per minute (bpm), inclusive.
. Systolic blood pressure is 90 to 140 mmHg, inclusive.
Questions worth asking your doctor
Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.
1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?
Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.
Questions for the trial coordinator
The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.
1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?
A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.
What they're measuring
1
The Proportion of Participants With Shigellosis Following Challenge With Shigella Sonnei 53G Through Day 63 in the Pooled Group of Participants Receiving Two Doses of 10^6 Cfu or 5x10^5 Cfu of WRSs2 Compared to Participants Receiving Two Doses of Placebo.
Timeframe: Day 57 through Day 63
Trial details
NCT IDNCT04242264
SponsorNational Institute of Allergy and Infectious Diseases (NIAID)
. Diastolic blood pressure is 55 to 90 mmHg, inclusive.
. Females of childbearing potential\*\* may enroll if subject has practiced adequate contraception\*\*\* = / \> 30 days prior to enrollment and agrees to continue adequate contraception for the entire study.
. Females of childbearing potential must have a negative urine or serum pregnancy test within 24 hours prior to enrollment.
0. Drug screen for opiates is negative.
1. BMI (Body Mass Index) between 18 and 40kg/m\^2.