Strategies to determine positive anti-SARS-CoV-2 memory T lymphocyte response during the evolution of an epidemic.

During SARS-CoV-2 pandemic, the assessment of immune protection of people at risk of severe infection was an important goal. The appearance of VOCs (Variant of Concern) highlighted the limits of evaluating immune protection through the humoral response. While the humoral response partly loses its neutralizing activity, the anti-SARS-CoV-2 memory T cell response strongly cross protects against VOCs becoming an indispensable tool to assess immune protection. We compared two techniques available in laboratory to evaluate anti-SARS-CoV-2 memory T cell response in a cohort of infected or vaccinated patients with different levels of risk to develop a severe disease: the ELISpot assay and the T-Cell Lymphocyte Proliferation Assay respectively exploring IFNγ production and cell proliferation. We showed that the ELISpot assay detected more anti-Spike memory T cell response than the Lymphocyte Proliferation Assay. We next observed that the use of two different suppliers as antigenic source in the ELISpot assay did not affect the detection of anti-Spike memory T cell response. Finally, we explored a new approach for defining the positivity threshold, using unsupervised mixed Gaussian modeling, challenging the traditional ROC curve used by the supplier. That will be helpful in endemic situation where it could be difficult to recruit "negative" patients.

Transfontanellar shear wave elastography of the neonatal brain for quantitative evaluation of white matter damage.

Cerebral white matter damage (WMD) is the most frequent brain lesion observed in infants surviving premature birth. Qualitative B-mode cranial ultrasound (cUS) is widely used to assess brain integrity at bedside. Its limitations include lower discriminatory power to predict long-term outcomes compared to magnetic resonance imaging (MRI). Shear wave elastography (SWE), a promising ultrasound imaging modality, might improve this limitation by detecting quantitative differences in tissue stiffness. The study enrolled 90 neonates (52% female, mean gestational age = 30.1 ± 4.5 weeks), including 78 preterm and 12 term controls. Preterm neonates underwent B-mode and SWE assessments in frontal white matter (WM), parietal WM, and thalami on day of life (DOL) 3, DOL8, DOL21, 40 weeks, and MRI at term equivalent age (TEA). Term infants were assessed on DOL3 only. Our data revealed that brain stiffness increased with gestational age in preterm infants but remained lower at TEA compared to the control group. In the frontal WM, elasticity values were lower in preterm infants with WMD detected on B-mode or MRI at TEA and show a good predictive value at DOL3. Thus, brain stiffness measurement using SWE could be a useful screening method for early identification of preterm infants at high WMD risk.Registration numbers: EudraCT number ID-RCB: 2012-A01530-43, ClinicalTrial.gov number NCT02042716.

Association between Portal Vein Thrombosis after Umbilical Vein Catheterization and Neonatal Asphyxia.

INTRODUCTION: Neonatal portal vein thrombosis (PVT) is frequently related to umbilical venous catheterization (UVC), but risk factors remain unclear. This study aims to analyze the variables associated to PVT in near- to full-term newborns with UVC, with a focus on newborns exposed to controlled therapeutic hypothermia (CTH) for hypoxic ischemic encephalopathy (HIE). METHODS: This is retrospective cohort study of infants delivered at or after 36 weeks and with a birthweight over 1,500 g. All infants were assessed for UVC location and PVT using ultrasonography performed between day 5 and day 10 after catheterization. RESULTS: Among 213 eligible patients, PVT was diagnosed in 57 (27%); among them, 54 (95%) were localized in the left portal vein branch. With all significant factors in univariate analysis considered, higher gestational age at birth (adjusted OR 1.35; 95% CI: 1.12-1.64, p = 0.002) and duration of UVC placement (adjusted OR 1.36; 95% CI: 1.11-1.67, p = 0.004) were the main risk factors of PVT. Among 87 infants who were cooled for HIE, 31 (36%) had PVT compared to 26 (21%) in infants without CTH. Using a multivariate model including variables linked to treatment procedures only, an increased PVT incidence was statistically associated with UVC duration (adjusted OR 1.33; 95% CI: 1.08; 1.63, p = 0.01) and CTH (adjusted OR 1.94; 95% CI: 1.04-3.65, p = 0.04). CONCLUSION: Left PVT was frequently observed in near- to full-term neonates with UVC. Among factors linked to treatment procedures, both duration of UVC and CTH exposure for HIE were found to be independent risk factors of PVT.