A contact study to evaluate the BCG vaccination programme in Seoul.

Area of Science:

• Pediatrics
• Infectious Diseases
• Public Health

Background:

• Tuberculosis (TB) remains a significant global health challenge, particularly in developing countries.
• The Bacillus Calmette-Guérin (BCG) vaccine is widely used for TB prevention in children.
• Assessing the real-world effectiveness of BCG vaccination programs is crucial for public health strategies.

Purpose of the Study:

• To evaluate the protective efficacy of the BCG vaccination program against tuberculosis in children up to 5 years of age.
• To determine the impact of BCG vaccination on tuberculosis incidence in household contacts of smear-positive pulmonary tuberculosis patients.

Main Methods:

• A contact study was conducted in Seoul involving 1993 children who were contacts of 4484 smear-positive pulmonary tuberculosis patients.
• 1223 children completed examinations; 806 showed evidence of BCG vaccination, and 417 did not.
• Data were stratified for potential confounding factors including age, sex, and socioeconomic variables.

Main Results:

• Tuberculosis cases were identified using radiological/clinical classification and a scoring system.
• For unvaccinated children, 84/80 cases were observed, compared to 45/46 cases in vaccinated children.
• After adjusting for age, BCG vaccination demonstrated a 74% protective effect (95% CI: 62%-82%) against tuberculosis.

Conclusions:

• The BCG vaccination program provides substantial protection against tuberculosis in young children.
• The observed protective effect of BCG was consistent across different types of tuberculosis disease.
• These findings support the continued implementation of BCG vaccination as a key public health intervention for pediatric tuberculosis prevention.