A Study of the Effect of an Oral Vaccine on the Digestive System

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Please answer a few questions to see if you may qualify.
Have questions? Please contact the study coordinator Eduardo Cervantes at Eduardo.cervantes@usda.gov or call (530) 236-6330
By clicking "Next", you're consenting to participate in this questionnaire. There are no right or wrong answers and everything you enter is confidential.
  1. *1. What is your age?
  2. *2. What is your height?
  3. *3. What is your weight?
  4. *4. What is your gender?
  5. *5. Are you pregnant or breastfeeding?
  6. *6. Are you allergic to vaccine components or aspirin?
  7. *7. Are you taking any anti-inflammatory medications?
    Such as Aspirin, Ibuprofen (Advil, Motrin, Midol), or Naproxen (Aleve, Naprosyn)
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"Volunteer for research at UC Davis and contribute to discoveries that may improve health care for you, your family, and your community!"
Age: 18 to 49 years old
Healthy Volunteers: Yes
Keywords: oral vaccine, gut health, leaky gut
Type: Biological study, Phase 1
15 Participants
The purpose of this study is to:

1. Determine whether ingesting the standard, 4-doses of a live, weakened typhoid fever vaccine will cause a temporary leaky gut and inflammation. Leaky gut is a condition when the gut lining becomes more permeable, or “leaky”, for substances in the gut to pass through to the tissues beneath it.

2. Compare the gut leakiness caused by this vaccine to the gut leakiness caused by a short-term ingestion of aspirin.

3. Examine whether the size of the body’s natural immune response to this vaccine is associated with gut leakiness and inflammation of similar size.
This study requires

Your participation in this study will involve thirteen (13) total visits to the WHNRC which includes:

  1. five (5) procedural visits of which 4 visits will last 5 hours per visit (1 hour for check-in, height, weight, blood pressure, and body temperature measurements, fasting blood draw, and consumption of a sugar drink and 4 hour wait time post-drink for urine collection) and 1 visit will last 5 ½ hours (same as above, but ½ hour extra for a urine pregnancy test and lactulose and aspirin counseling).

  2. two (2) procedural visits each lasting 1 hour per visit (for check-in, body measurements, and fasting blood draw).

  3. one (1) vaccine counseling and dispensing visit which also includes a urine pregnancy test.

  4. five (5) urine drop-off only visits.

Who can participate

Inclusion criteria:

  • Body Mass Index (BMI) 18.5 - 29.9 kg/m2

Exclusion criteria:

  • 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 immunosuppressive or antimitotic 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
Benefits and risks of participating

We cannot promise any benefits to you as a result of taking part in this research study.


The study doctor will discuss the risks associated with taking part in this research study.
We will pay you up to $372 if you complete all of the study visits. The compensation amount for each study visit is based on the hourly wage of $12/hour (CA state minimum wage) and the approximate time involved for each visit to WHNRC.
Study duration and period
Your participation in this 29-day study will involve: 1. A urine pregnancy test on Days 1 and 15 of the study. 2. An HIV blood test on Day 1 and Day 16. 3. 12-hour overnight fasts, i.e. 8 pm to 8 am, on eight (8) separate days, including the In-Person Screening visit. 4. Fasting blood draws on eight (8) separate days, including the In-Person Screening visit. 5. Consumption of a sugar drink consisting of (10 grams [1 tablespoon] lactulose, 5 grams [½ tablespoon] D-mannitol, and 2 grams [¼ tablespoon] sucralose) dissolved in 200 mL (7 fl oz) water on five (5) separate days. 6. Collection of urine at WHNRC and off-site on five (5) separate days. 7. Ingestion of two (2) doses of 975 mg (given as 3 capsules of 325 mg aspirin per capsule) over-the-counter aspirin per dose: one 975 mg dose to be ingested in the evening at home and one 975 mg dose to be ingested the following morning at home. 8. Ingestion of four (4) doses of Vivotif®, an oral live, attenuated typhoid fever vaccine (Ty21a) to be ingested every other day for six (6) days at home.
Recruitment period
From Aug. 7, 2019
Research Topic
  • Intestinal Permeability
  • Inflammation
  • Vaccine
  • Typhoid Fever

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