Pierre Goussard

Pediatric tuberculosis (TB) often presents as primary disease involving the mediastinal lymph nodes; however, its granuloma microenvironment remains poorly characterized because these population patient tissues are rarely available for study. Here, we use spatial transcriptomics to profile 60 granulomas from four children aged 4 to 36 months. We identified nine recurrent transcriptional microenvironments shared across granulomas, despite their marked histological heterogeneity. One macrophage-rich microenvironment showed strong hypoxia-associated activity and secreted phosphoprotein 1 (SPP1) enrichment. This microenvironment was present in both non-necrotic and necrotic lesions and overlapped with a Mtb-persistence macrophage signature previously identified in murine TB lymph nodes. Pathway analysis revealed the enrichment of both antimicrobial and regulatory programs within this microenvironment, suggesting partial immune control rather than uniform inflammatory or suppressive activity in this region. SPP1 expression was associated with regions enriched for both M1- and M2-like macrophages, suggesting a macrophage program that extends beyond conventional polarization classifications and may be influenced by the local granuloma microenvironment. We further observed a similar spatial association between hypoxia-associated activity and SPP1 expression in an independent adult TB dataset (pooled Spearman ρ=0.65) and validated this association at protein level by multiplex immunofluorescence in our pediatric TB granuloma sample. Overall, this study identified a hypoxia-associated SPP1 -enriched microenvironment that may contribute to incomplete bacterial clearance and could provide a framework for evaluating host-directed strategies to enhance sterilizing immunity without exacerbating tissue damage.

Background: The World Health Organization (WHO) recommends 4-month treatment for children with non-severe pulmonary tuberculosis, outlining eligibility criteria for settings with and without chest X-ray (CXR). We evaluated the diagnostic accuracy of the WHO eligibility criteria in settings without CXR (WHO-criteria) and developed clinical scores to support disease classification. Methods: Using data from an individual participant dataset (IPD; Decide TB) of children with confirmed/unconfirmed tuberculosis from four diagnostic studies (RaPaed-TB, Umoya, TB-Speed HIV, TB-Speed Decentralisation), we assessed the diagnostic accuracy of the WHO-criteria (with/without bacteriological testing) using expert CXR interpretation as a reference. We developed two multivariable logistic regression models with (Score 1) and without (Score 2) bacteriological testing, converted coefficients into integer scores with a threshold of >10 corresponding to a sensitivity ≥70%. Results: Of 2,383 children in the Decide TB IPD, 633 (26.6%) met the eligibility criteria for a 4-month regimen, of whom 116 (18.3%) had radiologically severe disease. With and without bacteriological testing, the WHO-criteria had sensitivities of 30.1% (95%CI: 20.3%-40.2%) and 21.7% (95%CI: 10.4%-34.5%), and specificities of 83.4% (95%CI: 80.2%-86.4%) and 81.9% (95%CI: 78.8%-84.9%), respectively. Score 1 and Score 2 had sensitivities of 41.1% (95%CI: 32.4%-49.5%) and 30.9% (95%CI: 22.6%-40.4%), and specificities of 77.3% (95%CI: 73.6%-80.8%) and 83.0% (95%CI: 79.5%-86.3%), respectively. Using WHO-criteria, 91/116 (78.4%) and 105/116 (90.5%) of children were at risk of undertreatment, compared to 68/116 (58.6%) and 80/116 (68.9%) when using developed scores. Conclusions: Developed scores demonstrated better sensitivity than WHO-criteria, however, performance remained suboptimal. Implementing shorter antituberculosis regimens without CXR remains challenging in children.

The evolving epidemiology of COVID-19, driven by successive SARS-CoV-2 variants of concern (VOCs), has prompted ongoing evaluation of their impact on disease severity in children. In low-and middle-income countries (LMICs), children experience a higher burden of severe respiratory illness and pneumonia-related mortality due to factors such as malnutrition, incomplete immuni­sation, HIV exposure or infection, tuberculosis, and disparities in access to healthcare services. Hospital-based paediatric studies from LMICs are therefore needed to understand how the epi­demiology and severity of COVID-19 have changed across pandemic waves. This study examined 354 hospitalised children with SARS-CoV-2 infection during the ancestral, pre-Omicron (Beta and Delta), and Omicron waves at Tygerberg Hospital in Cape Town, South Africa. We analysed data collected over an extended period, from March 2020 to June 2022. Statistical analyses were used to describe clinical characteristics across variant periods, and multivariable logistic regression models were applied to evaluate associations between potential risk factors and disease severity. Paediatric COVID-19 severity varied across VOC periods, with the highest burden observed during the pre-Omicron (Beta and Delta) waves. In multivariable analyses, younger age and circulating variants were associated with disease severity; CRP levels emerged as a marker associated with more severe illness, and corticosteroid treatment, while also associated with disease severity, reflects clinical response to more severe cases. These findings contribute to a better understanding of the epidemi­ology and clinical impact of COVID-19 in children and highlight the importance of context-specific surveillance and treatment strategies in resource-limited settings. What is already known on this topic: The epidemiology and clinical characteristics of COVID-19 evolved substantially with successive SARS-CoV-2 variants of concern, yet their impact on disease severity in children remains unclear. Existing ev­idence is largely limited to adult populations, children with mild-to-moderate illness, or well-resourced healthcare settings, leaving a critical gap in knowledge on how epidemiology and disease severity changed across pandemic waves among hospitalised children in low- and middle-income countries. What this study adds: While hospital-based studies in South Africa have substantially advanced understanding of paediatric SARS-CoV-2 infection, they have largely been limited to specific pandemic periods, individual variants, or specific levels of care. By analysing data over an extended period (March 2020 to June 2022), this study provides a systematic characterisation of changes in clinical presentation and risk factors for severe disease across the ancestral, pre-Omicron (Beta and Delta), and Omicron waves in hospitalised children. How this study might affect research, practice or policy: These findings underscore the need for age-stratified, variant-aware surveillance systems in low- and middle-income countries, where the burden of severe paediatric respiratory illness remains high. Access to oxygen in these settings also needs to be addressed. The association between young age and severe outcomes supports the prioritisation of infants in clinical monitoring and triage protocols. The prognostic value of CRP as an early risk stratification biomarker and the use of corticosteroids highlight the need for paediatric-specific trials to establish evidence-based treatment protocols in resource-limited settings.