Oral vaccine study probes gut barrier changes in healthy volunteers
NCT ID NCT04083950
First seen Jun 27, 2026 · Last updated Jun 27, 2026
Summary
This study looks at whether taking an oral typhoid vaccine temporarily makes the gut more 'leaky' and how the immune system responds. Ten healthy adults will receive the vaccine and a low-dose aspirin challenge. Researchers will measure sugar levels in urine and immune cells in blood to track changes.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- Ty21a typhoid oral vaccine (Vivotif) and aspirin
- What this could lead to
- If successful, this could help researchers understand how oral vaccines affect the gut barrier, potentially improving vaccine design.
- What could go wrong
- This is a very small, early-phase study with only 10 participants, so results may not apply broadly. The vaccine is known to be safe but may cause mild digestive upset.
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
-
Early phase 1
The earliest testing in people: a first look at safety, in a very small group.
- Participants
-
10 people
The number who actually took part.
- Started
-
Dec 2019
- Expected to finish
-
Sep 2026
An estimate. End dates often move.
- Lead sponsor
-
A government agency
The lead sponsor is a US federal agency other than the NIH.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
-
18 to 49 years
- Sex
-
Female participants only
- Healthy volunteers
-
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: * Body Mass Index (BMI) 18.5 - 29.9 kg/m2 Exclusion Criteria: * Has HIV/AIDS or another disease that affects the immune system * Has any kind of cancer * Decline to take an HIV blood test * Blood pressure greater than or equal to 140/90 mmhg * Pregnant or lactating women * Refusal to take a pregnancy test prior to the study * Refusal to use a method of birth control during the study * Allergy to vaccine components, i.e. Thimerosal and enteric-coated capsules * Allergy to oral typhoid vaccine * Allergy to aspirin * Daily use of blood thinners * Use of anti-inflammatory medications, i.e. nonsteroidal anti-inflammatory drugs (NSAID), aspirin, 3 or more times per month * Use of sulfonamides or antibiotics in the past 30 days * Use of anti-hypertensive drugs, i.e. beta blockers, diuretics, calcium channel blockers * Use of anti-malaria drugs, i.e. Mefloquine, chloroquine, and proguanil * Use of drugs that affect the immune system, i.e. immunosuppressants, immune-modifying drugs, corticosteroids, i.e. cortisone, prednisone, methylprednisolone, for 2 weeks or longer * Is taking cancer treatment with radiation or drugs * Greater than ten years residence in a typhoid-endemic area * Receipt of typhoid vaccine in the last 5 years * Receipt of any vaccine two weeks prior to receipt of Ty21a vaccine * Individuals at increased risk of developing complications from a live, bacterial vaccine * History of typhoid fever * History of primary immune deficiency or autoimmune disease * History of acute or chronic gastrointestinal (GI) disorder, i.e. Crohn's disease, irritable bowel syndrome, gastric ulcer * Diarrheal illness (defined as passing 3 or more abnormally loose or watery stool in a 24 hour period) or persistent vomiting 2 weeks prior to the study * History of bleeding disorder, including bleeding from the GI tract * History of chronic illnesses, i.e. diabetes, cardiovascular disease, cancer, gastrointestinal malabsorption or inflammatory diseases, kidney disease, autoimmune disorders, HIV, liver disease, including hepatitis B and C. * Asthma if taking medication on a daily basis * Recent surgery (within 3 months) * History of GI surgery * Recent hospitalization (within 3 months) * Acute febrile illness (within 2 weeks) * Unwillingness to discontinue consumption of artificial sweeteners in foods or drinks, i.e. sport drinks, coconut water, "diet" drinks and foods (possibly containing sucralose) * Not having at least one arm vein suitable for blood drawing * Unwilling or uncomfortable with blood draws seven times in 29 days * Regular blood or blood product donation and refusal to suspend donation * Current participation in another research study * Unable to fast for 12-16 hours
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
Contacts and locations
Locations
-
USDA, ARS, Western Human Nutrition Research Center
Davis, California, 95616, United States
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