High BCG Coverage and Falling Childhood TB in Japan

Tuberculosis (TB) in children remains a global public health concern, and understanding how vaccination programs affect childhood disease is essential for planning and prevention. In Japan, a universal Bacillus Calmette-Guérin (BCG) immunization program for infants under 13 months of age has been in place, and since 2005 the national notification system has required that a child’s BCG vaccination history be reported alongside clinical and treatment information. To examine what this surveillance data can tell us about childhood TB under a policy change introduced in 2013, Yuko Hamaguchi and colleagues conducted a descriptive analysis of national surveillance records. They focused on data covering the period 2007 to 2022 to capture long-term trends before and after the 2013 modification of the immunization program. By using the routine, nationwide reports collected through the notification system, the team aimed to describe vaccination coverage, the age at vaccination, and trends in reported childhood TB cases and incidence, and to explore whether the 2013 program change appeared to influence those patterns.

The study used Japan’s national surveillance data to map vaccination coverage and reported childhood TB over a 16-year window (2007–2022). The researchers report a very high median percentage of annual vaccination coverage for infants under 13 months at 97.0% across the observed period. They also found a shift in the typical timing of vaccination: before 2013, most infants received Bacillus Calmette-Guérin (BCG) at about 3 months of age, while since 2013 the majority were vaccinated at about 5 months. Over the follow-up period the number of childhood TB notifications fell by roughly 60%, and the annual incidence of childhood TB declined by about 40%. The analysis identified correlations between childhood TB and both the child’s age and their recorded BCG vaccination history. However, when specifically testing whether the 2013 modification to the BCG immunization program had a measurable effect, the change was not statistically significant in this surveillance-based analysis.

These findings from national surveillance data offer useful, evidence-based context for public health decisions and future research. The sustained high coverage of Bacillus Calmette-Guérin (BCG) vaccination and the concurrent declines in reported childhood TB suggest that Japan’s program is reaching nearly all infants and that broader trends in disease burden have moved downward over the study period. The observed correlation between childhood TB and both age and vaccination history highlights the continued importance of careful record-keeping and analysis of who is being vaccinated and when. At the same time, the lack of a clear, statistically significant effect tied specifically to the 2013 program modification underlines how difficult it can be to attribute changes in disease trends to a single policy adjustment when many factors and long time spans are involved. The authors present these national surveillance results as a resource that can help inform evaluations of BCG effectiveness and guide ongoing policy discussions about vaccination timing and monitoring.