Neonatal BCG vaccination in Ireland: evidence of its efficacy in the prevention of childhood tuberculosis.

Data from the 1986 and 1991 National Tuberculosis Survey were used, together with the Census of Population for those years, to try and determine whether bacille Calmette-Guerin (BCG) vaccination policy had any influence on the reported incidence of tuberculosis in the Republic of Ireland. The age-specific incidence of tuberculosis for the country as a whole and for local areas, was determined with respect to neonatal BCG vaccination. Based on these data, the reported incidence of tuberculosis in people aged 15 yrs or younger in areas without a policy of neonatal BCG was shown to be significantly higher compared to areas that use neonatal BCG vaccination (p = 1.5x10(-5) in 1986; and p = 1.0x10(-7) for 1991). It was estimated that some 646 vaccinations needed to be given to prevent one case of tuberculosis in 1986, and that the figure for 1991 was 551 vaccinations. This evidence supports a policy of continued neonatal bacille Calmette-Guerin vaccination in the population of the Republic of Ireland at present.