Assessing the Evidence for Universal Bacillus Calmette-Guèrin (BCG) Vaccination in England

Abstract

BCG is the only licensed vaccine against tuberculosis (TB). Due to the variable vaccine efficacy observed in trials and studies (0-80%), different strategies have been utilised worldwide, including universal or high-risk group vaccination targeting either neonates or children. In 2005 the UK shifted from a strategy of universal vaccination at age 13 years to targeted vaccination in neonates deemed at high risk, motivated by a decrease in notifications and increasing evidence that other control methods, such as contact tracing, were more economically viable. The original analyses assumed that TB rates would continue to decline, however we know now that this was not the case. We repeated the original analysis with the actual decrease in notification rates observed and conducted sensitivity analyses to establish the impact of changes to other model parameters. We then extended the model, which considered only white individuals, to include the heterogeneity of TB across the UK population, to produce improved estimates of BCG’s effectiveness. Lastly, we estimated the impact, in terms of additional notifications, of ending the BCG schools scheme over a range of possible years. We found that universal BCG vaccination was more effective than previously estimated with 1600 vaccines being required to prevent a single notification in the late 1990s, compared to the original estimate of 9300. Sensitivity analysis revealed that the number of vaccines to prevent a single case is highly sensitive to the decline in tuberculosis incidence over time and differences across age groups. Using more realistic assumptions about tuberculosis epidemiology, including the actual incidence over the last 30 years, suggests universal vaccination with BCG is more effective than previously predicted.

Date
Location
Warwick, United Kingdom
Links