BCG Revaccination Study in Diabetic and Non-Diabetic Adults

Tuberculosis Clinical Trial

Official title: A Clinical Study Comparing the Immune Response to Revaccination With Intradermal BCG and Aerosol BCG in Previously BCG Vaccinated Healthy Adult Volunteers With and Without Type 2 Diabetes

Status Recruiting

Clinical Trial Summary

The purpose of this study is to:

1. explore whether investigators can make BCG more effective by giving it in a different way. For this, aerosol inhaled BCG will be compared against the conventional BCG injection.

2. explore if there are differences in response to re-vaccination in healthy volunteers with and without Type 2 Diabetes.

It will involve 36 previously BCG-vaccinated participants. Bronchoscopies will be performed 14 days post-challenge to measure BCG recovered from bronchial samples. Blood tests will be taken to look at potential immunological markers of immunity.

Clinical Trial Description

Worldwide Tuberculosis (TB) remains the leading cause of death from an infectious disease. Key research priorities include the development of effective vaccine strategies.

Currently, the only licensed vaccine against TB is BCG (Bacille Calmette-Guérin) injected under the skin (intradermal). This works well as a single dose vaccination against TB in childhood but is often ineffective in adults. Previous studies have investigated the benefit of booster doses of intradermal BCG; although these have not shown a clear benefit in reducing the risk of getting a TB infection there is emerging evidence that it may reduce its duration. Certain groups of people are at a higher risk of infection with Mycobacterium tuberculosis, the bacterium that causes TB. An important risk group are those with Diabetes Mellitus, who are at an increased risk of both becoming infected and dying from the disease. The reason for this is not clear, however differences in the immune response to Mycobacteria are thought to be important. Strategies to improve protection of high risk groups including those with Diabetes are needed to reduce the global burden of TB.

Localised immune responses can differ to those seen systemically. Vaccine studies in other infectious diseases have shown that altering the route of administration can improve protection from disease. There is also evidence from animal studies that breathing in BCG as a fine mist (aerosol) can make the vaccine more effective than BCG injections. Previous clinical trials in our group (TB041 and TB044) and a current study (TB043) recruited healthy volunteers and showed that aerosol inhaled BCG can be safely administered. It has also been shown that BCG given this way can elicit immunological responses not seen in the systemic blood compartment. Vaccination with BCG through the respiratory tract therefore offers an important alternative to intradermal vaccination, which has the potential to be a more effective route for a boosting vaccine.

This study will provide data on the immune response to booster vaccination with BCG. The investigators will compare how these responses differ between routes of vaccine delivery (aerosol inhaled BCG versus intradermal vaccination), and also explore how the immune response to revaccination differs in adults with Type 2 diabetes (T2DM). The investigators will use the findings to explore the potential benefits of aerosol vaccination and to investigate differences in the immune responses in diabetic individuals to understand how the investigators can improve protection against TB in this high risk group.

It will involve a total of 36 previously BCG-vaccinated participants; 12 healthy volunteers will receive boosting vaccination with aerosol BCG, while a further 12 healthy volunteers will receive a boosting vaccination with intradermal BCG. The investigators will perform washings from the lungs (bronchoscopies) 14 days after BCG vaccination to measure immunological and bacterial responses. A further 12 previously BCG-vaccinated, healthy adult volunteers with T2DM will receive a boosting vaccination with intradermal BCG. The investigators will take blood samples from all volunteers to explore the immune response to BCG and to develop markers to understand who has developed a protective immune response to TB. ;

Related Conditions & MeSH terms

• Tuberculosis

• NCT number: NCT06246851
• Study type: Interventional
• Source: University of Oxford
• Contact: Vaccine Trials
• Phone: 01865 611413
• Email: vaccinetrials@ndm.ox.ac.uk
• Status: Recruiting
• Phase: N/A
• Start date: February 2024
• Completion date: November 2027