Is bacillus Calmette-Guerin revaccination necessary for Japanese children?

Background. Bacillus Calmette-Guerin (BCG) revaccination has been implemented in Japan among tuberculin-negative first grade primary and first grade junior high school students for decades. Controversies regarding the effectiveness of BCG revaccination and low incidence of tuberculosis (TB) among Japanese children prompted this study. Methods. Cost-effectiveness and cost-benefit analyses were conducted for a cohort of schoolchildren who underwent revaccination during 1996. The study population was a hypothetical cohort comprising 1.35 million first grade primary school and 1.51 million first grade junior high school students enrolled in 1996 at locations throughout Japan. Assuming 50% vaccine efficacy for revaccination, a 10-year duration of protection, and 5% annual discount rate, we calculated the total hypothetical number of TB cases averted, the cost and number of immunizations per TB case averted, and the benefit-cost ratio for the program. Results. The revaccination program for 1996 schoolchildren cohort would prevent 296 TB cases over a 10-year period at a cost of US$ 108,378 per case averted. About 4,963 immunizations would be required to prevent one child from developing TB. The benefit-cost ratio remained at 0.13 with baseline assumptions and ranged from 0.05 to 0.29 and from 0.02 to 0.74 for one-way and two-way sensitivity analyses, respectively. Conclusion. BCG revaccination among schoolchildren is not supported by available scientific and economic data. Based on the results of this study, current BCG revaccination policies in Japan and other countries should be reexamined. (C) 2002 American Health Foundation and Elsevier Science (USA).