Pediatric tuberculosis and BCG vaccine in Japan

Tuberculosis (TB) was a significant public health concern in Japan for over a century. While archaeological evidence suggests its presence as early as 1800 years ago, TB spread rapidly during Japan's modernization in the late 19th century. Initial control measures focused on patient isolation and the establishment of sanatoriums, later supported by the Tuberculosis Prevention Law. After World War II, public health interventions-such as mandatory case reporting, mass BCG vaccination, and the introduction of antimycobacterial agents like streptomycin-contributed to a marked decline in TB incidence and mortality. Treatment outcomes further improved with the development of multidrug chemotherapy. Mass BCG vaccination began in 1949, with universal childhood vaccination implemented in 1974. Japan employs a distinctive intradermal "stamp" method with multiple needles of BCG administration for less complication of a skin ulcer. The current strain, BCG Tokyo-172-1, developed in 1981, is used nationally and distributed globally through WHO-UNICEF programs. Pediatric TB has become rare, with fewer than 100 new cases annually. Most are identified through adults contact investigations; others are diagnosed based on clinical symptoms or screening. In recent years, the proportion of TB cases-including pediatric cases-among individuals born outside Japan, particularly from high-burden countries, has increased. As Japan transitions to a low TB burden setting, the continuation of universal BCG vaccination is under review. Selective vaccination of high-risk infants and enhanced screening among adults may offer more targeted and effective approaches.