ABSTRACT
Does the efficacy of BCG decrease with time since vaccination? A meta analyis
Laura C. Rodrigues; Jonathan A. C. Sterne; Ines Nobre Guedes
London School of Hygiene and Tropical Medicine
Estimates of the protective efficacy of BCG vaccination (BCG PE) against tuberculosis from different studies range from negative to over 90%. These estimates are heterogenous to a statistically significant degree. This study investigates the hypothesis that BCG PE decreases with time since vaccination, by performing a meta-analisys of the change in BCG-PE against tuberculosis over time observed in all nine randornised controlled trials which presented data separately for discrete time periods. For each trial, we derived log rate ratios for annual change in the rate of TB in controls and. the annual change in BCG PE. We also compared BCG PE in the first two years, and the last 10 years, to that in the rest of the trial, There was statistically significant heterogeneity between trials in the annual change in BCG PE. In six trials BCG PE decreased over time (in one of the trials this decrease was statistically significant) while in three of the trials it increased. The annual change in PE was not related to overall PE. Because of the heterogeneity, it would not be appropriate to calculate an overall trend in BCG PE with time.
Publication Dates
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Publication in this collection
30 Sept 2011 -
Date of issue
May 1995
