Evaluation of the BCG revaccination programme of schoolchildren in Finland.

Abstract

Objective: To evaluate the need for the BCG revaccination programme of schoolchildren in Finland.

Design: Investigating tuberculin sensitivity using the standard WHO Mantoux test and developing a model to estimate the risk of discontinuation, assuming that the annual incidence of tuberculosis within ten years after revaccination will remain at its present level; that the revaccination rate will be 2, 6 or 20%; and that the degree of protection will be 10, 20, 40 or 80%.

Setting and participants: Urban and rural schoolchildren--3,346 vaccinated with Copenhagen and 655 with Glaxo BCG vaccine at birth.

Results of data analysis: The annual incidence of tuberculosis was 4.2 per 100,000 in the age-group 15-24 years. BCG revaccination was given formerly to 20% of the age cohort but nowadays only 6% or 2% meet the criteria after receiving either Copenhagen or Glaxo BCG at birth. After discontinuation the expected increase of tuberculosis in the age-group 15-24 years is predicted to fall within the limits of 0.1-24 cases per year. If 2% are left without revaccination the increase will be 0.1-2.4 cases.

Conclusions: Due to the low annual incidence of tuberculosis in adolescents and to the small risk of increase the BCG revaccination programme has been discontinued from 1990 onwards.