PROJECT

Effectiveness of Adult BCG Vaccination in Preventing Tuberculosis among Selected High-Risk Groups: A Test-Negative, Matched Case-Control Study

April 2026 - March 2029

Objectives:

• Primary Objective:
To estimate the effectiveness of adult BCG vaccination in preventing microbiologically confirmed tuberculosis among selected high-risk groups in selected states of India.
• Secondary Objective:
To estimate the effectiveness of adult BCG vaccination in preventing clinically diagnosed tuberculosis among selected high-risk groups.

Study Overview:

India launched an adult BCG vaccination campaign in January 2024 targeting six groups considered to be at higher risk of tuberculosis: individuals with a history of TB, close contacts of TB patients, persons with diabetes mellitus, smokers, individuals with a body mass index (BMI) below 18 kg/m², and adults aged 60 years and above.This study will assess how effectively BCG vaccination protects adults in these high-risk groups against tuberculosis. The study will be conducted through selected Tuberculosis Units and healthcare facilities in six states of India. It will use existing healthcare and National TB Elimination Programme systems and diagnostic services.

Study Approach:

• This is a *test-negative, matched case-control study* that will be conducted across *100 Tuberculosis Units (TUs) in six states—Odisha, Madhya Pradesh, Himachal Pradesh, Maharashtra, Andhra Pradesh and Haryana*. The participating sites will have functional TB diagnostic services and will have implemented adult BCG vaccination for at least one year.
• Adults aged 18 years and above from the eligible high-risk groups who are evaluated for presumptive TB at participating health facilities will be screened. Appropriate diagnostic investigations, including *nucleic acid amplification testing (NAAT) and chest X-ray*, will be undertaken as applicable. Individuals with microbiologically confirmed TB will be classified as cases, while eligible individuals who test negative for TB and have a normal chest X-ray will serve as controls.
• BCG vaccination status will be assessed using available programme records and other sources of vaccination information. Data will be collected through existing programme platforms, including Ni-kshay and TB-WIN, with appropriate data quality and verification procedures. Cases and controls will be matched to improve comparability and reduce potential bias.

Expected Public Health Impact:

The study will generate evidence on the effectiveness of adult BCG vaccination in preventing tuberculosis among high-risk adults in selected states of India. The findings will help inform evidence-based decisions on the targeting and potential expansion of adult BCG vaccination strategies in India and contribute to strengthening interventions under the National TB Elimination Programme.