Table 2

Proposed conceptual framework for understanding the effect of BCG vaccination

SettingFollow-up period*Predominant reactivation profileBCG effectiveness
Declining burdenEarlyEarly progression from early infection/exposureHigh
Declining burdenLateLate progression from early infection/exposureHigh
Sustained high burdenEarlyEarly progression from early infection/exposureHigh
Sustained high burdenLateEarly progression from late infection/exposureNil†
  • *Early: approximately the first 3 to 5 years following vaccination; late: greater than 5 years following vaccination.

  • †Adverse effect not excluded.