Can vaccines reshape gut immunity? a new study digs deep
NCT ID NCT03705585
First seen Sep 04, 2026 · Last updated Sep 04, 2026
Summary
This study looks at how the body responds to vaccines against typhoid fever and cholera. Healthy adults who are already scheduled for a colonoscopy or upper endoscopy will either receive one or both vaccines before the procedure, after it, or not at all. Researchers will collect blood, saliva, stool, and tissue samples to see how the vaccines change immune cells and bacteria in the gut. The goal is to better understand the body's reaction to these vaccines, which are already approved for travelers.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- Typhoid oral vaccine (Vivotif) and cholera oral vaccine (Vaxchora)
- What this could lead to
- If successful, this could reveal how these vaccines trigger immune responses and interact with gut bacteria, potentially improving vaccine design and delivery.
- What could go wrong
- This is an early exploratory study focused on immune markers, not on preventing disease. Results may not translate into practical changes, and individual responses to vaccines vary.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
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Phase 4
Runs after approval, following long-term safety and how well the treatment works in everyday use.
- Participants
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About 240 people
The number the study aims to enrol. It can still change while the study runs.
- Started
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Nov 2018
- Expected to finish
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May 2029
An estimate. End dates often move.
- Lead sponsor
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Other sponsor
The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
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18 years and older
- Sex
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Anyone
- Healthy volunteers
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Accepted
You do not need to have the condition being studied to take part.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: * 1\. Age 18 years and older * 2\. Already scheduled to undergo an EGD or colonoscopy for screening, surveillance, or a medically-indicated work-up at the University of Maryland Medical Center (main campus or Midtown) * 3\. Able to provide written informed consent prior to initiation of any study procedures * 4\. Healthy, as defined by considered fit to undergo outpatient elective EGD/colonoscopy by the evaluating health care provider Exclusion Criteria: * 1\. Pregnancy or nursing mother * 2\. Known coagulopathy or bleeding disorder preventing mucosal biopsy * 3\. History of Crohn's disease or ulcerative colitis * 4\. For Subjects undergoing lower endoscopy (colonoscopy) only: Surgical removal of the ileocecal valve or any part of the small or large intestine (non-complicated appendectomy will be considered eligible) * 5\. Allergic reaction to oral typhoid or cholera vaccine in the past * 6\. Immunosuppression from illness or treatment, including 1. immune-deficiency disorders such as Human Immunodeficiency Virus (HIV) or Acquired Immunodeficiency Syndrome (AIDS) 2. leukemia, lymphoma, or cancers (localized non-melanoma skin cancers which are deemed inactive should be considered eligible) * 7\. Receipt of any other vaccine two weeks prior to receipt of Ty21a or CVD 103-HgR * 8\. Positive urine pregnancy test (HCG) prior to colonoscopy or vaccination
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As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
How to take part
Only the study team decides who joins. These are the ways to reach them.
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The places running it
1 site. The list below names each one and where it is.
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The official record
ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.
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A doctor treating you
A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.
Contacts and locations
Locations
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University of Maryland, Baltimore, Center for Vaccine Development and Global Health
RECRUITINGBaltimore, Maryland, 21201, United States