Lalor, M. K. | Search bioRxiv

bioRxiv2019

A model of tuberculosis clustering in low incidence countries reveals more on-going transmission in the United Kingdom than the Netherlands between 2010 and 2015.

Tuberculosis (TB) is a major public health threat, including in low TB incidence countries, through a combination of imported infection and onward transmission. Using data from the Enhanced Tuberculosis Surveillance system in the United Kingdom (UK) and the Netherlands (NL) Tuberculosis Register, we developed a mathematical model of TB importation and transmission in low-incidence settings. We apply this method to compare the effective reproduction number for TB, the contribution of importation and the role of superspreaders in the UK and the NL. We estimate that on average, between 2010 and 2015, a TB case generated 0{middle dot}41(0{middle dot}30,0{middle dot}60) secondary cases in the UK, and 0{middle dot}24(0{middle dot}14,0{middle dot}48) secondary cases in the NL. A majority of cases did not generate any secondary cases. Recent transmission accounted for 26% (21%,36%) of UK cases and 19%(11%,31%) of NL cases. We predict that reducing UK transmission rates to those observed in NL would result in 538(266,818) fewer cases annually in the UK. This methodology reveals common transmission mechanisms across two low-incidence countries and can be applied to other settings. Control policies aimed at limiting spread have a role to play in eliminating TB in low incidence countries.

epidemiology↗

bioRxiv2018

Exploring the effects of BCG vaccination in patients diagnosed with tuberculosis: observational study using the Enhanced Tuberculosis Surveillance system

BackgroundBacillus Calmette-Guerin (BCG) is one of the most widely-used vaccines worldwide. BCG primarily reduces the progression from infection to disease, however there is evidence that BCG may provide additional benefits. We aimed to investigate whether there is evidence in routinely-collected surveillance data that BCG vaccination impacts outcomes for tuberculosis (TB) cases in England.\n\nMethodsWe obtained all TB notifications for 2009-2015 in England from the Enhanced Tuberculosis surveillance system. We considered five outcomes: All-cause mortality, death due to TB (in those who died), recurrent TB, pulmonary disease, and sputum smear status. We used logistic regression, with complete case analysis, to investigate each outcome with BCG vaccination, years since vaccination and age at vaccination, adjusting for potential confounders. All analyses were repeated using multiply imputed data.\n\nResultsWe found evidence of an association between BCG vaccination and reduced all-cause mortality (aOR:0.76 (95%CI 0.64 to 0.89), P:0.001) and weak evidence of an association with reduced recurrent TB (aOR:0.90 (95%CI 0.81 to 1.00), P:0.056). Analyses using multiple imputation suggested that the benefits of vaccination for all-cause mortality were reduced after 10 years.\n\nConclusionsWe found that BCG vaccination was associated with reduced all-cause mortality in people with TB although this benefit was less pronounced more than 10 years after vaccination. There was weak evidence of an association with reduced recurrent TB.\n\nHighlightsO_LIFound evidence of an association between BCG vaccination and reduced all-cause mortality in TB cases.\nC_LIO_LIWeaker evidence of an association between BCG vaccination and reduced repeat TB episodes in TB cases.\nC_LIO_LIThere was little evidence of an association with other TB outcomes.\nC_LIO_LIWe explored the identified associations by age and time since vaccination.\nC_LI

epidemiology↗