Evaluation of the BCG revaccination programme of schoolchildren in Finland.

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.