Post-acute prevalence of occult pulmonary embolism after hospitalisation for Covid-19

Background: During hospitalization for Covid-19 the prevalence of pulmonary embolism (PE) is ~15%. Occult PE may be undiagnosed during hospitalization. Also, after discharge, factors such as residual (local) inflammation and relative physical inactivity may predispose to PE. Aim(s): To study the presence of occult PE and pulmonary perfusion defects three months after discharge from hospitalization for Covid-19. Method(s): In this prospective study we performed CT pulmonary angiography (CTPA) in adults three months after discharge from hospitalization for moderate-to-critical Covid-19. Exclusion criteria: therapeutic anticoagulation, diagnosed PE during hospitalization, CTPA contra-indications. Primary outcome measure was presence of PE. Secondary outcomes were wedge shaped perfusion defects on subtraction iodine maps, D-dimer concentration, presence of Years criteria at follow-up, and pulmonary parenchymal abnormalities. Result(s): 26 patients (65% male, 61 (SD10) y, hospital length of stay 11 (IQR9-15) days, 34% ICU treatment) underwent CTPA at 13 (SD2) weeks after discharge. 25 patients (96%) had no evidence for PE while one post-ICU patient demonstrated a suspected partial occlusion of a subsegmental pulmonary artery. No wedge shaped perfusion defects were found. D-Dimer values were <1000 ng/ml in all patients and none had Years criteria. Extent of parenchymal abnormalities decreased compared to acute phase (CT severity score 7 (SD5) vs 13 (SD5), p=0.004). Conclusion(s): Prevalence of occult PE three months after discharge from hospitalization for Covid-19 was negligible in our sample. CTPA should not be routinely performed in these patients. .

[89Zr]Df-crefmirlimab PET/CT imaging to assess the in vivo distribution of CD8+ T-cells in hospitalized COVID-19 patients

Aim/Introduction: COVID-19 patients may present with lymphopenia. The degree of lymphopenia, in particular reduced CD8+ T-cell numbers, is strongly correlated with clinical deterioration and ICU admission [1,2]. It has been postulated that lymphopenia in COVID-19 is caused by;1) sequestration of CD8+ T-cells in peripheral tissues (e.g. lung) [3], 2) accelerated maturation and exhaustion [4,5] or 3) decreased lymphopoiesis [6]. The lack of data on in vivodistribution of CD8+ T-cells hampers a more thorough understanding of this critical prognostic factor. We aim to assess differences in the in vivo distribution of CD8+ T-cells in patients with proven SARS-CoV-2 presenting with lymphopenia or with normal lymphocyte counts, using [89Zr]Df-crefmirlimab PET/CT imaging. Material(s) and Method(s): This is a prospective, observational non-randomized pilot study in hospitalized patients with microbiologically proven SARS-CoV-2 infection. The prior use of immune suppressive medication was an exclusion criterion. Whole body [89Zr]Df-crefmirlimab PET/CT scan were acquired at 24 hrs after intravenous injection of 1.5mg protein dose labelled with 37 MBq (1 mCi)89Zr. Peripheral blood samples were collected for multi-colour flowcytometry to phenotype homing receptors and immune senescence markers, and transcriptomics. Result(s): Three patients were enrolled (all male, average 83 yrs (78-89 yrs)), admitted at 5.3 days (2-10 days) after onset of symptoms and scanned at 2.7 days (2-4 days) after admission. Two patients completed vaccination (2x plus booster), one patient was not vaccinated. Two patients had with lymphocyte count <1.0 x10e9/L and one patient had normal lymphocyte counts on admission. One patient required oxygen suppletion 3L/min. PET/CT scans showed remarkable differences in uptake in the upper respiratory tract versus lower respiratory tract, involvement of distant organs and distribution of CD8+ T-cells across secondary lymphoid organs, spleen and hematopoietic system. Quantification of the scans, flow cytometry and transcriptomic analyses are ongoing. Conclusion(s): In vivo imaging of CD8+ T-cells in hospitalized COVID-19 patients reveals distinct patterns of CD8+ T-cell distribution in early stages of localized infection versus systemic involvement at later stages. Translational data on T-cell phenotyping is currently processed and will be presented.

On-line purchases of organic food in the context of the COVID-19 pandemic in the Czech Republic

The Czech organic food market is on the rise. Organic food production has seen a significant boom in terms of sales volumes, which enabled opening of new shopping channels for consumers. In 2020, a number of strict measures was introduced with the intention to curb the outbreak of the Covid-19 pandemic, which also affected the organic food distribution and preferred places of purchase. Due to all the lockdowns and limitations, on-line shopping entered the scene as a new potential tool for organic food market development. The aim of this research is to identify the organic food shopping patterns of internet users during March and April 2020 in the context of freshly introduced governmental measures, and to identify dependencies according to selected socio-demographic respondents' characteristics. The results show that respondents' level of education and their age are the key determining factors when it comes to their on-line organic food purchases.