Background: BCG vaccine protects against the severe forms of tuberculosis (TB) in children. Several low-prevalence countries are reviewing their policy, usually shifting from universal vaccination to vaccination of infants in high-risk groups only. We combined an epidemiologic analysis with a cost-effectiveness analysis to evaluate the cost-effectiveness of targeted strategies.
Methods: We fitted a static model to the data to estimate vaccine efficacy and risk of disease. We applied our method to the Dutch situation, analyzing severe TB cases in high-risk group children age 0-5, between 1996 and 2003. We considered the current strategy targeting immigrant children from high-incidence countries, and a proposed strategy additionally targeting children from 3 lower-incidence, but higher-immigration, countries.
Results: In the absence of vaccination, the annual risk of developing severe TB for a child in the current target group is 3/100,000, while BCG vaccination reduces this risk by 73%. Therefore about 9000 children would need to be vaccinated to prevent 1 case. Vaccinating children from high-incidence countries would then cost about Euro 4,500 per discounted disability-adjusted life year averted. In the extended target group, the risk of disease is somewhat lower with a similar vaccine effectiveness, so costs are raised.
Conclusions: The current Dutch BCG strategy, as well as the proposed inclusion of immigrant children from Turkey, Surinam and former Yugoslavia, is on average cost-effective. However, the low number of both vaccinated and unvaccinated severe TB cases leads to broad confidence intervals on vaccine efficacy, highlighting the difficulty associated with decision-making in low-prevalence settings.