BCG vaccine: durable protection against TB for up to 20 years

  • Katelaris AL & al.
  • J Infect Dis
  • 1 Jan 2020

  • International Clinical Digest
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Takeaway

  • Bacillus Calmette-Guérin (BCG) vaccination appears to prevent Mycobacterium tuberculosis (TB) acquisition in adult contacts and limits progression to latent tuberculosis infection (LTBI).

Why this matters

  • Consider BCG vaccine history and time since vaccination in at-risk adults presenting post-TB exposure to facilitate best management strategies. 
  • Ensure familiarity with ECDC BCG vaccine scheduler.

Key results

  • 3453 participants, 3399 included in complete-case analysis, median age 32 (interquartile range, 25-43) years.
  • LTBI prevalence:
    • 27.5% (951) overall;
    • 27.0% (809) among vaccinated vs 31.4% (142) among unvaccinated;
    • OR, 0.81 (P=.054).
  • Multivariate, BCG-LTBI association:
    • OR, 0.70 (P=.0017).
    • Vaccine effectiveness (VE): 30% (95% CI, 13%-44%).
  • BCG protection (ORs, 95% CIs) with vaccination at age
  • 11-20 years ago: 0.55 (0.33-0.90); 
  • >20 years ago: 0.78 (0.60-1.00).
  • BCG protection (ORs; 95% CIs) with vaccination at age >2 years for adults vaccinated:
    • ≤10 years ago: 0.31 (0.15-0.63); 
    • 11-20 years ago: 0.73 (0.48-1.10); and
    • >20 years ago: 0.67 (0.46-0.98).
  • Study design

    • Cross-sectional analysis assessing BCG VE durability against LTBI in at-risk, UK adults.
    • Funding: National Institute for Health Research.

    Limitations

    • Observational. 
    • Measurement errors, misclassifications.
    • Self-report bias.
    • Residual confounding.
    • Interferon-gamma release assay (IGRA) specificity.