Examining how antibiotics affect immune responses to vaccines

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

This clinical trial investigates the impact of gut microbiota depletion through antibiotics on immune responses to the BCG vaccine in healthy adults aged 18-35. It consists of two sub-studies: the first assesses the immune response to a BCG challenge after antibiotic treatment, while the second evaluates the response to a Yellow Fever vaccine. Participants are randomized to receive either antibiotics or a placebo before vaccination, followed by a re-challenge with the BCG vaccine or Yellow Fever vaccine. The study aims to determine if antibiotic-induced changes in gut bacteria affect vaccine efficacy.

Why it matters

Who can join: the full rules

Inclusion Criteria:

* 18-35 years old
* Provided a signed and dated informed consent form
* BCG naïve (Arm 1) and BCG and YF vaccine naïve (Arm 2)
* Willing to take short antibiotic course
* Willing to undergo a punch biopsy (Arm 1)
* Willing to have up to 7 blood samples and 3 stool samples collected over 5-7 months
* Not pregnant or intending to get pregnant for the duration of the study (a pregnancy test will be offered to females)

Exclusion Criteria:

* Previous BCG vaccination
* Previous YF vaccination or YFV infection (only applies to participants included in the Yellow Fever Vaccine challenge sub-study)
* Evidence of TB infection (assessed through a questionnaire - IGRA to confirm if needed)
* People with contraindications for BCG vaccination:

  * malignancies involving bone marrow or lymphoid systems, primary or secondary immunodeficiencies, HIV infection
  * moderate/severe skin disease including eczema, dermatitis or psoriasis
  * requiring immunosuppressive drugs or other immune modifying drugs e.g. corticosteroids, non-biological immunosuppressants, biological agents (such as monoclonal antibodies against tumour necrosis factor (TNF)-alpha)
* People with contraindications to YF vaccination:

  * History of thymus disease, including myasthenia gravis, thymoma, thymectomy, DiGeorge syndrome, thymic damage from chemoradiotherapy or graft-versus-host disease
  * YF vaccination is contraindicated in immunocompromised individuals, including individuals who have HIV infection, primary immunodeficiencies (including inherited IFNAR1 deficiency), or are taking corticosteroids or other immunosuppressive agents and haematopoietic stem cell transplant recipients
  * People who have had a haematopoietic stem cell transplant
  * Individuals with history of severe allergic reactions to egg or chicken proteins
* Pregnant or breastfeeding or planning to become pregnant
* History of renal disease/insufficiency
* Tattoo obscuring BCG vaccination site(s)
* Any history of severe allergic reaction or anaphylaxis to vaccination or antibiotics
* People with chronic serious underlying illness
* Have received any prescribed oral or intravenous antibiotic in the 28 days prior to study visits 1 and 4 (including isoniazid, rifampicin, streptomycin and ethambutol as these particular antibiotics have activity against M. bovis)
* Have received any vaccinations in the 28 days prior to study visits 1 and 4

Where it's running

• South Australian Health and Medical Research Institute
  Adelaide, South Australia, Australia Recruiting

Study contacts

• Principal investigator: David Lynn — South Australian Health and Medical Research Institute
• Study coordinator: David Lynn
• Email: david.lynn@sahmri.com
• Phone: +61 8 8128 4053

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.