Evaluating the neonatal BCG vaccination programme in Ireland

Retrospective cohort study exploring the impact of universal Tuberculosis (TB) vaccination cessation on the epidemiology of paediatric TB in Ireland, 2011-2021

BACKGROUND

Since 2010, Ireland's Tuberculosis (TB) crude incidence rate (CIR) remains below 10 per 100,000 population defining it as a low TB incidence country. Ireland maintained a universal BCG vaccination programme until its discontinuation in 2015 due to lack of vaccine supply. This study explores the impact of discontinuing a national universal BCG vaccination programme on the epidemiology of paediatric TB cases.

METHODS

We retrospectively analysed TB notifications aged 0-6 years old reported to the Irish National TB Surveillance System between 2011 and 2021. Key epidemiological characteristics and temporal trends in TB age specific incidence rates (ASIRs) were compared between 0 and 6 year old cases born during a period of universal BCG vaccination (2007-2015) and 0-6 year old cases born after BCG vaccination ceased (2015-2021).

RESULTS

No significant temporal trend was detected in the overall 0-6 year old ASIR by notification year during 2011-2021 (IRR:0.95; 0.86-1.1). However, the temporal trend for cases born during universal vaccination showed a significant decline (0.74; CIR: 0.62-0.89) while cases born after BCG vaccination ceased had a non-significant increase (1.2; CIR: 0.73-1.86). A significantly declining temporal trend was detected among cases born in Ireland during universal vaccination (IRR:0.73; 0.62-0.86), but no significant trend was detected in the cases born outside Ireland during universal vaccination (IRR:0.83; 0.53-1.31). No significant trend was detected in cases born after vaccination ceased in either cases born in Ireland (IRR:1.0; 0.60-1.65) or those born outside Ireland (IRR:0.64; 0.29-1.40).

CONCLUSIONS

Universal BCG cessation has not yet directly impacted on TB cases among 0-6 year olds in Ireland. However, interruption of the previously declining temporal trend in this cohort during universal vaccination may be an early warning of a future increase. Paediatric TB cases remain an important cohort for timely surveillance to monitor trends in this primarily unvaccinated cohort to evaluate the long-term effects.

Reassessing the evidence for universal school-age BCG vaccination in England and Wales: re-evaluating and updating a modelling study

OBJECTIVES

In 2005, England and Wales switched from universal BCG vaccination against tuberculosis (TB) disease for school-age children to targeted vaccination of neonates. We aimed to recreate and re-evaluate a previously published model, the results of which informed this policy change.

DESIGN

We recreated an approach for estimating the impact of ending the BCG schools scheme, correcting a methodological flaw in the model, updating the model with parameter uncertainty and improving parameter estimates where possible. We investigated scenarios for the assumed annual decrease in TB incidence rates considered by the UK's Joint Committee on Vaccination and Immunisation and explored alternative scenarios using notification data.

SETTING

England and Wales.

OUTCOME MEASURES

The number of vaccines needed to prevent a single notification and the average annual additional notifications caused by ending the policy change.

RESULTS

The previously published model was found to contain a methodological flaw and to be spuriously precise. It greatly underestimated the impact of ending school-age vaccination compared with our updated, corrected model. The updated model produced predictions with wide CIs when parameter uncertainty was included. Model estimates based on an assumption of an annual decrease in TB incidence rates of 1.9% were closest to those estimated using notification data. Using this assumption, we estimate that 1600 (2.5; 97.5% quantiles: 1300, 2000) vaccines would have been required to prevent a single notification in 2004.

CONCLUSIONS

The impact of ending the BCG schools scheme was found to be greater than previously thought when notification data were used. Our results highlight the importance of independent evaluations of modelling evidence, including uncertainty, and evaluating multiple scenarios when forecasting the impact of changes in vaccination policy.

COVID-19 and Beyond: Exploring Public Health Benefits from Non-Specific Effects of BCG Vaccination

Bacille Calmette–Guérin (BCG) vaccination, widely used throughout the world to protect against infant tuberculous meningitis and miliary tuberculosis (TB), can provide broad non-specific protection against infectious respiratory diseases in certain groups. Interest in BCG has seen a resurgence within the scientific community as the mechanisms for non-specific protection have begun to be elucidated. The impact of the COVID-19 pandemic on nearly every aspect of society has profoundly illustrated the pressure that respiratory infections can place on a national healthcare system, further renewing interest in BCG vaccination as a public health policy to reduce the burden of those illnesses. However, the United States does not recommend BCG vaccination due to its variable effectiveness against adult TB, the relatively low risk of Mycobacterium tuberculosis infection in most of the United States, and the vaccine’s interference with tuberculin skin test reactivity that complicates TB screening. In this review, we explore the broad immune training effects of BCG vaccination and literature on the effects of BCG vaccination on COVID-19 spread, disease severity, and mortality. We further discuss barriers to scheduled BCG vaccination in the United States and how those barriers could potentially be overcome.

Health economic evaluation of current vaccination strategies and new vaccines against tuberculosis: a systematic review

Introduction: Bacillus Calmette-Guérin (BCG) is the only licensed vaccine for tuberculosis, but its effectiveness is limited and varies by age. New candidate vaccines are currently being investigated. In response to the declining incidence of TB, practices relating to BCG vaccination have changed in various countries in recent years. A valid cost-effectiveness study is therefore needed in order to assist decision-makers in the implementation of cost-effective strategies for BCG vaccination. Areas covered: Studies involving economic evaluations of BCG vaccination were reviewed in order to present current findings concerning a range of BCG vaccination strategies in a variety of regions, target populations, and vaccine types. The Quality of Health Economic Studies (QHES) instrument was used to assess the quality of the studies included in the analysis. Expert opinion: Most of the studies showed a favorable economic profile of BCG vaccination. Selective strategies seem the most cost-effective option for low-incidence areas. Varying results on revaccination strategies did not lead to any conclusive finding on the cost-effectiveness of the strategies. A novel vaccine - either a BCG replacement or booster vaccine that provides better protection, especially in adults - has the potential to enhance the cost-effectiveness of vaccinating against tuberculosis.

Impact of BCG vaccination on incidence of tuberculosis disease in southern Ireland

Background

Tuberculosis (TB) is the ninth leading cause of death worldwide and the leading cause from a single infectious agent. Bacillus Calmette-Guerin (BCG) is the only licensed vaccine for TB, yet its efficacy remains debated with variations in vaccine sub-strains, policies, and practices observed across the world. Three BCG vaccination policies were implemented across adjoining regions in the South West of Ireland from 1972; neonatal vaccination (vaccinated Region-A), vaccination of children aged 10–12 years (vaccinated Region-B) and no vaccination (unvaccinated Region-C). The aim of this study is to examine the impact of different BCG vaccination policies on incidence of TB disease in the South of Ireland over a 13-year period.

Methods

Cases of active TB disease from 2003 to 2016 were identified through surveillance data. Residential addresses for each case were geocoded using the Google Maps API. Addresses were linked to 2011 census population data and to Local Health Offices BCG coverage data for study regions A-C. A steady-state population was assumed to calculate the 13-year incidence of TB disease. Using SatScan (v9.4.4), spatial clusters were identified at a small area level with the spatial scan statistic based on the discrete Poisson probability distribution.

Results

Of 621 TB disease cases identified, 510 could be linked to the study area based on the reported addresses. The median age was 42 years (range 4 months - 94 years), 65% male and 66% Irish born. The incidence of TB disease was higher in the unvaccinated population, region-C 132/100,000 (95% CI 116–150) versus vaccinated region-A 56/100,000 (95%CI 45–69) and region-B 44/100,000 (95%CI 29–63). A spatial cluster analysis identified a single high-risk cluster in region -C where the relative risk (vs. the areas outside of the cluster) was 4.94 (95% CI 4.03 to 5.96).

Conclusion

Our study demonstrates significant regional variation in the incidence of TB in demographically similar populations based on BCG vaccination policy. This observation is particularly noteworthy in a country with low TB disease incidence such as Ireland. These findings strengthen existing data demonstrating efficacy of BCG vaccination for primary prevention of TB disease.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4026-z) contains supplementary material, which is available to authorized users.

Economic Evaluation of Selective Neonatal Bacillus Calmette-Guérin Vaccination of High-risk Infants in Ireland

BACKGROUND

In Western Europe, currently only Ireland and Portugal continue to provide universal neonatal bacillus Calmette-Guérin (BCG) vaccination programs, despite not being considered as high tuberculosis (TB) incidence countries. Other European countries only vaccinate infants considered at high risk of contracting TB. We evaluated the cost-effectiveness of selective BCG vaccination compared with strategies of universal and no vaccination.

METHODS

An economic model was used to simulate a cohort from birth to life expectancy, taking the perspective of the publicly funded healthcare system. BCG protection was modeled to last 15 years. International vaccine efficacy data were combined with Irish epidemiologic and cost data. The model took into account long-term sequelae associated with TB meningitis and severe adverse reactions relating to the BCG vaccine. A fully probabilistic model was used to incorporate uncertainty across all parameters.

RESULTS

At &OV0556;139,557 per quality-adjusted life year, selective vaccination was not cost-effective relative to a program of no vaccination. The incremental cost-effectiveness of universal vaccination was &OV0556;2.55 million per quality-adjusted life year relative to selective vaccination. There was substantial uncertainty regarding the effectiveness of BCG vaccination. The cost-effectiveness of selective vaccination could be substantially improved by reducing the cost of administering the vaccine.

CONCLUSIONS

In the absence of changes to other aspects of TB control, a switch to selective vaccination will result in increased cases of childhood TB. Although not considered cost-effective, selective vaccination may be preferable to no vaccination until other changes to TB control may be implemented to reduce the risk of TB in children.

Combined Diagnosis of Systemic Lupus Erythematosus and Tuberculosis in an Irish Adolescent Female

Systemic lupus erythematosus (SLE) is an autoimmune disease of unknown aetiology, which can affect any organ system. Tuberculosis (TB) is a common infection in SLE because of immune dysregulation associated with the latter. We report a case of an adolescent female who presented with a year's history of polyarticular arthralgia and fever. Physical examination revealed a large left effusion that needed drainage. Investigations revealed a combined diagnosis of SLE and TB. Management comprised quadruple anti-TB therapy and SLE treatment. She made a steady recovery and has maintained a stable state from the lupus perspective.