Key performance indicators of COVID-19 contact tracing in Belgium from September 2020 to December 2021.

The goal of tracing, testing, and quarantining contacts of infected individuals is to contain the spread of infectious diseases, a strategy widely used during the COVID-19 pandemic. However, limited research exists on the effectiveness of contact tracing, especially with regard to key performance indicators (KPIs), such as the proportion of cases arising from previously identified contacts. In our study, we analyzed contact tracing data from Belgium collected between September 2020 and December 2021 to assess the impact of contact tracing on SARS-CoV-2 transmission and understand its characteristics. Among confirmed cases involved in contact tracing in the Flemish and Brussels-Capital regions, 19.1% were previously identified as close contacts and were aware of prior exposure. These cases, referred to as 'known' to contact tracing operators, reported on average fewer close contacts compared to newly identified individuals (0.80 versus 1.05), resulting in fewer secondary cases (0.23 versus 0.28). Additionally, we calculated the secondary attack rate, representing infections per contact, which was on average lower for the 'known' cases (0.22 versus 0.25) between December 2020 and August 2021. These findings indicate the effectiveness of contact tracing in Belgium in reducing SARS-CoV-2 transmission. Although we were unable to quantify the exact number of prevented cases, our findings emphasize the importance of contact tracing as a public health measure. In addition, contact tracing data provide indications of potential shifts in transmission patterns among different age groups associated with emerging variants of concern and increasing vaccination rates.

Tuberculosis Transmission in a Primary School and a Private Language School. An Estimation of Infectivity.

Introduction: Belgium is a country with low incidence of tuberculosis (TB) and a very low number of TB cases in children. Children in contact with an adult smear-positive TB case are at high risk of transmission. Early diagnosis is important as young children have a significant predisposition of developing TB disease. In this paper, we describe two outbreaks after exposure to, respectively, two teachers with smear-positive pulmonary TB: one in a primary school, a nursery teacher, and another in a private language school. Methods: An exposure investigation was carried out in both index cases household and school, according to the stone-in-the-pond principle. The tuberculin skin test (TST) was used a screening tool. The time elapsed between TB diagnosis in the index case and contact investigation was, respectively, 1 and 3 weeks. If this initial test was negative, it was repeated after a "window period" of ≥8 weeks. Results: Index cases showed a transmission rate of, respectively, 13 and 40% in their classes at school, defined as casual contacts. The proximity of contact increased the risk of infection. TB disease was observed in, respectively, 4 and 11% of all the casual contacts; all of them were children younger than 5 years old. TB-infected and children with active TB disease had good compliance with recommended treatment. Uptake of chemoprophylaxis during the "window period" was poor, respectively, only 32-42%, in children under 5 years with an initially negative TST. Discussion: The World Health Organization recommends to screen all young children (<5 years old) who have close contact with a person affected by pulmonary TB and to initiate Latent tuberculosis infection treatment even before infection can be demonstrated, after ruling out active TB disease. Despite this knowledge, a small percentage of the children younger than 5 years with no proof of infection was treated with the proposed chemoprophylactic treatment, in both cases. Conclusion: This exposure investigation of two teachers detects high transmission among family contacts and school casual contacts. Recommendations for chemoprophylactic treatment in children <5 years showed low compliance, reflecting the difficulty of communication to staff, parents, and children in a school outbreak. It is essential to develop a new approach for this vulnerable group of patients. This approach could be improved, applied, and evaluated by National TB Control Programs, involving public and private health services. Public health authorities play a role in raising public awareness about the risks of TB for young children.

Molecular epidemiology of Mycobacterium tuberculosis complex in Brussels, 2010-2013.

The tuberculosis (TB) incidence rate in Brussels-Capital Region is 3-fold higher than in Belgium as a whole. Eight years after the realization of initial prospective population-based molecular epidemiology investigations in this Region, a similar study over the period 2010-2013 was conducted. TB strains isolated from 945 patients were submitted to genotyping by standardized 24-locus-MIRU-VNTR typing and spoligotyping. The phylogenetic analysis showed that the LAM (16.7%) and Haarlem (15.7%) branches are the two most prevalent TB lineages circulating in Brussels. Analysis of the MDR subgroup showed an association with Beijing strains (39.9%) and patients native of Eastern Europe (40.7%). Genotyping detected 113 clusters involving 321 patients, giving a recent transmission index of 22.9%. Molecular-guided epidemiological investigations and routine surveillance activities revealed family transmission or social contact for patients distributed over 34 clusters. Most of the patients were foreign-born (75.7%). However, cluster analysis revealed only limited trans-national transmission. Comparison with the previous study shows a stable epidemiological situation except for the mean age difference between Belgian-born and foreign-born patients which has disappeared. This study confirms that molecular epidemiology has become an important determinant for TB control programs. However, sufficient financial means need to be available to perform all required epidemiological investigations.

Cost-effectiveness of screening for active cases of tuberculosis in Flanders, Belgium.

OBJECTIVE: To assess the cost-effectiveness of the tuberculosis screening activities currently funded by the Flemish government in Flanders, Belgium. METHODS: After estimating the expenses for 2013-2014 of each of nine screening components - which include high-risk groups, contacts and people who are seeking tuberculosis consultation at a centre for respiratory health care - and the associated costs per active case of tuberculosis identified between 2007 and 2014, we compared the cost-effectiveness of each component. The applied perspective was that of the Flemish government. FINDINGS: The three most cost-effective activities appeared to be the follow-up of asylum seekers who were found to have abnormal X-rays in initial screening at the Immigration Office, systematic screening in prisons and contact investigation. The mean costs of these activities were 5564 (95% uncertainty interval, UI: 3791-8160), 11 603 (95% UI: 9010-14 909) and 13 941 (95% UI: 10 723-18 201) euros (€) per detected active case, respectively. The periodic or supplementary initial screening of asylum seekers and the screening of new immigrants from high-incidence countries - which had corresponding costs of €51 813 (95% UI: 34 855-76 847), €126 236 (95% UI: 41 984-347 822) and €418 359 (95% UI: 74 975-1 686 588) - appeared much less cost-effective. Between 2007 and 2014, no active tuberculosis cases were detected during screening in the juvenile detention centres. CONCLUSION: In Flanders, tuberculosis screening in juvenile detention centres and among new immigrants and the periodic or supplementary initial screening of asylum seekers appear to be relatively expensive ways of detecting people with active tuberculosis.

Nontuberculous mycobacteria among pulmonary tuberculosis patients: a retrospective Belgian multicenter study.

OBJECTIVES: Currently, there are no European data about the frequency and clinical significance of nontuberculous mycobacteria (NTM) grown from respiratory samples during the treatment of tuberculosis (TB). We determined the frequency and clinical significance of NTM isolated before or during pulmonary tuberculosis treatment in Belgian laboratories. METHODS: We conducted a nationwide retrospective multicenter cohort study on the co-isolation of TB and NTM in Belgium. Starting from laboratory data between 2006 and 2013, possible TB-NTM co-isolations were searched for. RESULTS: A total of 2569 unique culture-positive pulmonary tuberculosis cases were included in the study. Only 35 (1.4%) of these TB cases had an NTM co-isolated, and two of these 35 fulfilled the ATS criteria for NTM lung disease. CONCLUSION: A very low prevalence of 1.4% NTM co-isolations was found in Belgian patients with culture-proven pulmonary TB.

Health Impact Assessment of a Predicted Air Quality Change by Moving Traffic from an Urban Ring Road into a Tunnel. The Case of Antwerp, Belgium.

BACKGROUND: The Antwerp ring road has a traffic density of 300,000 vehicles per day and borders the city center. The 'Ringland project' aims to change the current 'open air ring road' into a 'filtered tunneled ring road', putting the entire urban ring road into a tunnel and thus filtering air pollution. We conducted a health impact assessment (HIA) to quantify the possible benefit of a 'filtered tunneled ring road', as compared to the 'open air ring road' scenario, on air quality and its long-term health effects. MATERIALS AND METHODS: We modeled the change in annual ambient PM2.5 and NO2 concentrations by covering 15 kilometers of the Antwerp ring road in high resolution grids using the RIO-IFDM street canyon model. The exposure-response coefficients used were derived from a literature review: all-cause mortality, life expectancy, cardiopulmonary diseases and childhood Forced Vital Capacity development (FVC). RESULTS: Our model predicts changes between -1.5 and +2 µg/m³ in PM2.5 within a 1,500 meter radius around the ring road, for the 'filtered tunneled ring road' scenario as compared to an 'open air ring road'. These estimated annual changes were plotted against the population exposed to these differences. The calculated change of PM2.5 is associated with an expected annual decrease of 21 deaths (95% CI 7 to 41). This corresponds with 11.5 deaths avoided per 100,000 inhabitants (95% CI 3.9-23) in the first 500 meters around the ring road every year. Of 356 schools in a 1,500 meter perimeter around the ring road changes between -10 NO2 and + 0.17 µg/m³ were found, corresponding to FVC improvement of between 3 and 64ml among school-age children. The predicted decline in lung cancer mortality and incidence of acute myocardial infarction were both only 0.1 per 100,000 inhabitants or less. CONCLUSION: The expected change in PM2,5 and NO2 by covering the entire urban ring road in Antwerp is associated with considerable health gains for the approximate 352,000 inhabitants living in a 1,500 meter perimeter around the current open air ring road.

Towards tuberculosis elimination: an action framework for low-incidence countries.

This paper describes an action framework for countries with low tuberculosis (TB) incidence (<100 TB cases per million population) that are striving for TB elimination. The framework sets out priority interventions required for these countries to progress first towards "pre-elimination" (<10 cases per million) and eventually the elimination of TB as a public health problem (less than one case per million). TB epidemiology in most low-incidence countries is characterised by a low rate of transmission in the general population, occasional outbreaks, a majority of TB cases generated from progression of latent TB infection (LTBI) rather than local transmission, concentration to certain vulnerable and hard-to-reach risk groups, and challenges posed by cross-border migration. Common health system challenges are that political commitment, funding, clinical expertise and general awareness of TB diminishes as TB incidence falls. The framework presents a tailored response to these challenges, grouped into eight priority action areas: 1) ensure political commitment, funding and stewardship for planning and essential services; 2) address the most vulnerable and hard-to-reach groups; 3) address special needs of migrants and cross-border issues; 4) undertake screening for active TB and LTBI in TB contacts and selected high-risk groups, and provide appropriate treatment; 5) optimise the prevention and care of drug-resistant TB; 6) ensure continued surveillance, programme monitoring and evaluation and case-based data management; 7) invest in research and new tools; and 8) support global TB prevention, care and control. The overall approach needs to be multisectorial, focusing on equitable access to high-quality diagnosis and care, and on addressing the social determinants of TB. Because of increasing globalisation and population mobility, the response needs to have both national and global dimensions.