Targeted BCG vaccination against severe tuberculosis in low-prevalence settings: epidemiologic and economic assessment.

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.