BCG and New Preventive Tuberculosis Vaccines: Implications for Healthcare Workers

Mapping the existing body of knowledge on new and repurposed TB vaccine implementation: A scoping review

There is global consensus on the urgent need for a safe and effective TB vaccine for adults and adolescents to improve global TB control, and encouragingly, several promising candidates have advanced to late-stage trials. Significant gaps remain in understanding the critical factors that will facilitate the successful implementation of new and repurposed TB vaccines in low- and middle-income countries (LMICs), once available. By synthesizing the existing body of knowledge, this review offers comprehensive insights into the current state of research on implementation of these adult and adolescent vaccines. This review explores four key dimensions: (1) epidemiological impact, (2) costing, cost-effectiveness, and/or economic impact, (3) acceptability, and the (4) feasibility of implementation; this includes implementation strategies of target populations, and health system capabilities. Results indicate that current research primarily consists of epidemiological and costing/cost-effectiveness/economic studies in India, China, and South Africa, mainly modelling with M72/AS01, BCG revaccination, and hypothetical vaccines. Varying endpoints, vaccine efficacies, and vaccination coverages were used. Globally, new, and repurposed TB vaccines are estimated to save millions of lives. Economically, these vaccines also demonstrate promise with expected cost-effectiveness in most countries. Projected outcomes were dependent on vaccine characteristics, target population, implementation strategy, timing of roll out, TB burden/country context, and vaccination coverage. Potential barriers for vaccine acceptability included TB-related stigma, need for a second dose, and cost, while low pricing, community and civil society engagement and heightened public TB awareness were potential enablers in China, India, and South Africa. Potential implementation strategies considered spanned from mass campaigns to integration within existing vaccine programs and the primary target group studied was the general population, and adults and adolescents. In conclusion, future research must have broader geographical representations to better understand what is needed to inform tailored vaccine programs to accommodate diverse country contexts and population groups to achieve optimal implementation and impact. Furthermore, this review underscores the scarcity of research on acceptability of new and repurposed TB vaccines and their delivery among potential beneficiaries, the most promising implementation strategies, and the health system capabilities necessary for implementation. The absence of this knowledge in these areas emphasizes the crucial need for future research to ensure effective TB vaccine implementation in high burden settings worldwide.

Patterns of Systemic Disease Diagnoses among Medical Professionals in Taiwan: Statistical Analysis and Data Mining

INTRODUCTION

Although high-risk work environments and heavy workload expose medical professionals to long-term risks of disease, no comprehensive analysis has been conducted on the corresponding risks of diseases to each type of medical professionals. This study pre-analyzed the risks of medical professionals in developing various systemic diseases in Taiwan to provide a comprehensive examination of the differences between each type of systemic disease.

METHODS

From the secondary databases of 2002-2013, 15,407 medical professionals were selected for analysis. A chi-squared test and logistic regression were performed to identify the relationship between types of medical professionals and systemic diseases. The life trajectories of diagnosis sequence of the medical professionals were illustrated accordingly.

RESULTS

The physicians were the most vulnerable to infectious, parasitic, and digestive diseases. This was possibly associated with their work characteristics and occupational risks.

CONCLUSION

According to the life trajectories, all types of the medical professionals exhibited a similar trend in the orders of risks to each type of systemic disease, which suggests that their work environment exposes them to real risks of health hazard.

A Modern Perspective on Vaccinating Healthcare Service Providers in India: A Narrative Review

Healthcare providers (HCPs) are at increased risk of acquisition and transmission of infectious disease. Vaccinating HCPs is an essential preventive measure to protect them and their patients against communicable diseases, while positively and directly impacting the functioning of the healthcare system. In India, healthcare represents one of the largest employment sectors with 3.8 million HCPs; however, there is limited awareness of national immunisation guidelines for the Indian HCP population. Data from communicable disease outbreaks across India suggest inadequate vaccination rates amongst HCPs; studies have reported influenza and varicella vaccination rates as low as 4.4% and 16%, respectively. In this review, we discuss data highlighting the impact of insufficient vaccination coverage, barriers to vaccination, and the lack of immunisation guidelines amongst HCPs in India. COVID-19 vaccination programmes for HCPs have been critical in slowing the pandemic in India. This provides an opportunity to raise awareness about the importance of vaccines amongst HCPs in India.

Healthcare staff perceptions towards influenza and potential COVID-19 vaccination in the 2020 pandemic context

The COVID-19 pandemic generated renewed focus on infectious disease transmission in healthcare settings. This study aimed to evaluate staff perceptions towards influenza vaccination in the COVID-19 context. All healthcare workers within a major UK tertiary referral hospital were invited to answer a survey conducted from September 2^nd to 13^th, 2020. In all, 593 responses were received across a spectrum of roles; 44% reported they were more likely to get an influenza vaccine this year due to COVID-19; however, 10% felt that an influenza vaccine was less important due to social distancing. Additional questions evaluated intention to receive COVID-19 vaccination. There were substantial differences of opinion between staff groups.

High risk of Mycobacterium tuberculosis infection among medical and nursing students in Indonesia: a 1-year prospective study

BACKGROUND

Medical and nursing students entering their clinical programmes are at increased risk for tuberculosis (TB) in TB-endemic settings. Relatively little is known about Mycobacterium tuberculosis infection among such students in high-endemic countries.

METHODS

We examined M. tuberculosis infection among medical and nursing students starting clinical training in Bandung, Indonesia using interferon-γ release assay (IGRA) QuantiFERON-TB Gold Plus. IGRA-negative students had a repeat test after 1 y and logistic regression was used to identify factors associated with IGRA positivity or conversion.

RESULTS

There were 379 students included in this study: 248 (65.4%) were medical students and 131 (34.6%) were nursing students. Of 379 students, 70 (18.5%) were IGRA positive at baseline. Of 293 IGRA-negative students with 1-y results, 26 (8.9%) underwent IGRA conversion. Being a medical student (adjusted relative risk [ARR] 5.15 [95% confidence interval {CI} 1.82 to 14.59], p=0.002) and participation in sputum collection or bronchoscopy were associated with IGRA conversion (ARR 2.74 [95% CI 1.29 to 5.79], p=0.008).

CONCLUSIONS

Medical and nursing students entering clinical training are at high risk of M. tuberculosis infection and need improved infection prevention and control strategies.

Current Guidelines for Protecting Health Workers from Occupational Tuberculosis Are Necessary, but Not Sufficient: Towards a Comprehensive Occupational Health Approach

Health workers globally are at elevated occupational risk of tuberculosis infection and disease. While a raft of guidelines have been published over the past 25 years on infection prevention and control (IPC) in healthcare, studies in different settings continue to show inadequate implementation and persistence of risk. The aim of this commentary is to argue, based on the literature and our own research, that a comprehensive occupational health approach is an essential complement to IPC guidelines. Such an approach includes a health system framework focusing on upstream or mediating components, such as a statutory regulation, leadership, an information system, and staff trained in protective disciplines. Within the classical prevention framework, primary prevention needs to be complemented by occupational health services (secondary prevention) and worker's compensation (tertiary prevention). A worker-centric approach recognises the ethical implications of screening health workers, as well as the stigma perceived by those diagnosed with tuberculosis. It also provides for the voiced experience of health workers and their participation in decision-making. We argue that such a comprehensive approach will contribute to both the prevention of occupational tuberculosis and to the ability of a health system to withstand other crises of infectious hazards to its workforce.

BCG revaccination boosts adaptive polyfunctional Th1/Th17 and innate effectors in IGRA+ and IGRA- Indian adults

BACKGROUNDBacille Calmette-Guérin (BCG) vaccine is protective against Tuberculosis (TB) in children, but its efficacy wanes with age. Consequently, determining if BCG revaccination augments anti-TB immunity in young adults in TB endemic regions is vital.METHODSTwo hundred healthy adults, BCG vaccinated at birth, were tested for their IFN-γ release assay (IGRA) status. Of these, 28 IGRA+ and 30 IGRA- were BCG revaccinated, and 24 IGRA+ and 23 IGRA- subjects served as unvaccinated controls. T and innate cell responses to mycobacterial antigens were analyzed by 14-color flow cytometry over 34 weeks.RESULTSIFN-γ and/or IL-2 Ag85A- and BCG-specific CD4+ and CD8+ T cell responses were boosted by revacciantion at 4 and 34 weeks, respectively, and were > 2-fold higher in IGRA+ compared with IGRA- vaccinees. Polyfunctional Ag85A, BCG, and mycobacterium tuberculosis (Mtb) latency Ag-specific (LTAg-specific) CD4+ T cells expressing up to 8 cytokines were also significantly enhanced in both IGRA+ and IGRA- vaccinees relative to unvaccinated controls, most markedly in IGRA+ vaccinees. A focused analysis of Th17 responses revealed expansion of Ag85A-, BCG-, and LTAg-specific total IL-17A+,IL-17F+,IL-22+, and IL-10+ CD4+ T cell effectors in both IGRA+ and IGRA- subjects. Also, innate IFN-γ+ NK/γδ/NKT cell responses were higher in both IGRA+ and IGRA- vaccinees compared with controls. This is the first evidence to our knowledge that BCG revaccination significantly boosts antimycobacterial Th1/Th17 responses in IGRA+ and IGRA- subjects.CONCLUSIONThese data show that BCG revaccination is immunogenic in IGRA- and IGRA+ subjects, implying that Mtb preinfection in IGRA+ subjects does not impact immunogenicity. This has implications for public health and vaccine development strategies.FUNDINGThis work was funded principally by DBT-NIH (BT/MB/Indo-US/HIPC/2013).

High risk for latent tuberculosis infection among medical residents and nursing students in India

Defining occupational latent tuberculosis infection (LTBI) risk among healthcare workers is needed to support implementation of prevention guidelines. Prospective cohort study of 200 medical residents and nursing students in India was conducted May 2016-December 2017. Tuberculin skin test (TST) and QuantiFERON TB Gold Test-in-tube (QFT-GIT) were performed at study entry and 12 months. Primary outcome was incident LTBI (≥10mm TST induration and/or ≥0.35IU/mL QFT-GIT) at 12 months; secondary outcomes included baseline LTBI prevalence and risk factors for incident and prevalent LTBI using Poisson regression. Among 200, [90 nursing students and 110 medical residents], LTBI prevalence was 30% (95% CI, 24-37); LTBI incidence was 26.8 (95% CI, 18.6-37.2) cases per 100 person-years and differed by testing method (28.7 [95% CI, 20.6-38.9] vs 17.4 [95% CI, 11.5-25.4] cases per 100 person-years using TST and QFT-GIT, respectively). Medical residents had two-fold greater risk of incident LTBI than nursing students (Relative Risk, 2.16; 95% CI, 1.05-4.42). During study period 6 (3%) HCWs were diagnosed with active TB disease. Overall, median number of self-reported TB exposures was 5 (Interquartile Range, 1-15). Of 60 participants with prevalent and incident LTBI who were offered free isoniazid preventive therapy (IPT), only 2 participants initiated and completed IPT. High risk for LTBI was noted among medical residents compared to nursing students. Self-reported TB exposure is underreported, and uptake of LTBI prevention therapy remains low. New approaches are needed to identify HCWs at highest risk for LTBI.

Postexposure Effects of Vaccines on Infectious Diseases

We searched the PubMed database for clinical trials and observational human studies about postexposure vaccination effects, targeting infections with approved vaccines and vaccines licensed outside the United States against dengue, hepatitis E, malaria, and tick-borne encephalitis. Studies of animal models, serologic testing, and pipeline vaccines were excluded. Eligible studies were evaluated by definition of exposure; attempts to distinguish pre- and postexposure effects were rated on a scale of 1 to 4. We screened 4,518 articles and ultimately identified for this review 14 clinical trials and 31 observational studies spanning 7 of the 28 vaccine-preventable diseases. For secondary attack rate, the following medians were found for postexposure vaccination effectiveness: hepatitis A, 85% (interquartile range (IQR), 28; n = 5 sources); hepatitis B, 85% (IQR, 22; n = 5 sources); measles, 83% (IQR, 21; n = 8 sources); varicella, 67% (IQR: 48; n = 9 sources); smallpox, 45% (IQR, 39; n = 4 sources); and mumps, 38% (IQR, 7; n = 2 sources). For case fatality proportions resulting from rabies and smallpox, the median vaccine postexposure efficacies were 100% (IQR, 0; n = 6 sources) and 63% (IQR, 50; n = 8 sources), respectively. Many available vaccines can modify or preclude disease if administered after exposure. This postexposure effectiveness could be important to consider during vaccine trials and while developing new vaccines.

Mycobacterium bovis BCG and New Vaccines for the Prevention of Tuberculosis

Tuberculosis infects millions of people worldwide and remains a leading global killer despite widespread neonatal administration of the tuberculosis vaccine, bacillus Calmette-Guérin (BCG). BCG has clear and sustained efficacy, but after 10 years, its efficacy appears to wane, at least in some populations. Fortunately, there are many new tuberculosis vaccines in development today, some in advanced stages of clinical trial testing. Here we review the epidemiological need for tuberculosis vaccination, including evolving standards for administration to at risk individuals in developing countries. We also examine proven sources of immune protection from tuberculosis, which to date have exclusively involved natural or vaccine exposure to whole cell mycobacteria. After summarizing evidence for the use and efficacy of BCG, we detail the most promising new candidate vaccines against tuberculosis. The global need for a new tuberculosis vaccine is acute and huge, but clinical trials to be completed in the coming few years are likely either to identify a new tuberculosis vaccine or to substantially reframe how we understand immune protection from this historical scourge.