The duration of protection of school-aged BCG vaccination in England: A population-based case-control study

Punam Mangtani, Patrick Nguipdop-Djomo, Ruth H. Keogh, Jonathan A.C. Sterne, Ibrahim Abubakar, Peter G. Smith, Paul E.M. Fine, Emilia Vynnycky, John Watson, David Elliman, Marc Lipman, Laura C. Rodrigues

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25 Citations (Scopus)

Abstract

Background: Evidence of protection from childhood Bacillus Calmette-Guerin (BCG) against tuberculosis (TB) in adulthood, when most transmission occurs, is important for TB control and resource allocation. Methods: We conducted a population-based case-control study of protection by BCG given to children aged 12-13 years against tuberculosis occurring 10-29 years later. We recruited UK-born White subjects with tuberculosis and randomly sampled White community controls. Hazard ratios and 95% confidence intervals (CIs) were estimated using case-cohort Cox regression, adjusting for potential confounding factors, including socioeconomic status, smoking, drug use, prison and homelessness. Vaccine effectiveness (VE=1 - hazard ratio) was assessed at successive intervals more than 10 years following vaccination. Results: We obtained 677 cases and 1170 controls after a 65% response rate in both groups. Confounding by deprivation, education and lifestyle factors was slight 10-20 years after vaccination, and more evident after 20 years. VE 10-15 years after vaccination was 51% (95% CI 21, 69%) and 57% (CI 33, 72%) at 15-20 years. Subsequently, BCG protection appeared to wane; 20-25 years VE=25% (CI -14%, 51%) and 25-29 years VE=1% (CI -84%, 47%). Based on multiple imputation of missing data (in 17% subjects), VE estimated in the same intervals after vaccination were similar [56% (CI 33, 72%), 57% (CI 36, 71%), 25% (-10, 48%), 21% (-39, 55%)]. Conclusions: School-aged BCG vaccination offered moderate protection against tuberculosis for at least 20 years, which is longer than previously thought. This has implications for assessing the cost-effectiveness of BCG vaccination and when evaluating new TB vaccines.

Original languageEnglish
Article numberdyx221
Pages (from-to)193-201
Number of pages9
JournalInternational Journal of Epidemiology
Volume47
Issue number1
DOIs
Publication statusPublished - 1 Feb 2018

Keywords

  • BCG vaccine
  • Bacillus Calmette-Guerin
  • Duration
  • Effectiveness
  • England
  • Epidemiology
  • Prevention and control
  • Tuberculosis

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