The booster effect with repeat tuberculin testing in children and its relationship to BCG vaccination

S Afr Med J. 1990 Apr 21;77(8):387-9.


One hundred and twenty-seven children, aged 6 months - 14 years, attending a day-care centre in Pretoria had two Mantoux tuberculin tests performed 8 weeks apart. On initial testing 19.7% of the children had reactions greater than or equal to 10 mm and positive tests were commoner in the older children--who had received BCG vaccination twice. On repeat testing a significant increase in the mean tuberculin reaction size was noted and 13% of the children converted to tuberculin positivity. Since an extensive search revealed no evidence of active tuberculosis in either children or adults at the day-care centre, it was concluded that the observed enhancement of the tuberculin reactions was due to the booster effect. This phenomenon was most marked in preschoolers with a BCG scar. It is important to recognise that boosting can occur in children and may be confused with true conversion to tuberculin positivity caused by infection with Mycobacterium tuberculosis.

MeSH terms

  • Adolescent
  • BCG Vaccine*
  • Child
  • Child, Preschool
  • False Positive Reactions
  • Humans
  • Infant
  • Tuberculin Test*
  • Tuberculosis / prevention & control
  • Vaccination


  • BCG Vaccine