Setting: Norway, Sweden, Denmark and Finland have low incidence rates (IRs) of tuberculosis (TB) but the use of bacille Calmette-Guérin (BCG) vaccination has varied.
Objective: To assess if different IRs among persons at low risk in the four countries could be related to the different use of BCG vaccination, and to estimate the number of adolescent BCG vaccinations needed to prevent one case of TB in Norway.
Design: The study period was 1996-2005. In part A, IRs for cases classified as 'born in country/national' in the EuroTB database in all four countries were calculated. In part B, the IRs among persons born in Norway and Sweden with two parents from low-incidence countries were calculated for cases registered in the respective national TB registers. In both parts, IRs and IR ratios among 0-14-year-olds and 15-29-year-olds were compared and related to different BCG vaccination policies.
Results and conclusions: Our results are consistent with a protective effect of newborn BCG vaccination in native-born 0-14-year-olds in Finland, and of adolescent BCG vaccination in 15-29-year-olds in Norway. The Norwegian BCG vaccination programme conferred 61-64% protection to 15-29-year-olds; however, 21699-25125 vaccinations were needed to prevent one case.