ABSTRACT
Introduction: Recurrent positive results in quantitative reverse transcriptase-PCR (qRT-PCR) tests have been commonly observed in COVID-19 patients. We aimed to construct and validate a reliable risk stratification tool for early predictions of non-critical COVID-19 survivors' risk of getting tested re-positive within 30 days. Methods: We enrolled and retrospectively analyzed the demographic data and clinical characters of 23,145 laboratory-confirmed cases with non-critical COVID-19. Participants were followed for 30 days and randomly allocated to either a training (60%) or a validation (40%) cohort. Multivariate logistic regression models were employed to identify possible risk factors with the SARS-CoV-2 recurrent positivity and then incorporated into the nomogram. Results: The study showed that the overall proportion of re-positive cases within 30 days of the last negative test was 24.1%. In the training cohort, significantly contributing variables associated with the 30-day re-positivity were clinical type, COVID-19 vaccination status, myalgia, headache, admission time, and first negative conversion, which were integrated to build a nomogram and subsequently translate these scores into an online publicly available risk calculator (https://anananan1.shinyapps.io/DynNomapp2/). The AUC in the training cohort was 0.719 [95% confidence interval (CI), 0.712-0.727] with a sensitivity of 66.52% (95% CI, 65.73-67.30) and a specificity of 67.74% (95% CI, 66.97-68.52). A significant AUC of 0.716 (95% CI, 0.706-0.725) was obtained for the validation cohort with a sensitivity of 62.29% (95% CI, 61.30-63.28) and a specificity of 71.26% (95% CI, 70.34-72.18). The calibration curve exhibited a good coherence between the actual observation and predicted outcomes. Conclusion: The risk model can help identify and take proper management in high-risk individuals toward the containment of the pandemic in the community.
ABSTRACT
SARS-CoV-2 vaccine booster dose can induce a robust humoral immune response, however, its cellular mechanisms remain elusive. Here, we investigated the durability of antibody responses and single-cell immune profiles following booster dose immunization, longitudinally over 6 months, in recipients of a homologous BBIBP-CorV/BBIBP-CorV or a heterologous BBIBP-CorV/ZF2001 regimen. The production of neutralizing antibodies was dramatically enhanced by both booster regimens, and the antibodies could last at least six months. The heterologous booster induced a faster and more robust plasmablast response, characterized by activation of plasma cells than the homologous booster. The response was attributed to recall of memory B cells and the de novo activation of B cells. Expanded B cell clones upon booster dose vaccination could persist for months, and their B cell receptors displayed accumulated mutations. The production of antibody was positively correlated with antigen presentation by conventional dendritic cells (cDCs), which provides support for B cell maturation through activation and development of follicular helper T (Tfh) cells. The proper activation of cDC/Tfh/B cells was likely fueled by active energy metabolism, and glutaminolysis might also play a general role in promoting humoral immunity. Our study unveils the cellular mechanisms of booster-induced memory/adaptive humoral immunity and suggests potential strategies to optimize vaccine efficacy and durability in future iterations.
ABSTRACT
Cardiac injury is a common complication of the coronavirus disease 2019 (COVID-19), and is associated with adverse clinical outcomes. In this study, we aimed to reveal the association of cardiac injury with coagulation dysfunction. We enrolled 181 consecutive patients who were hospitalized with COVID-19, and studied the clinical characteristics and outcome of these patients. Cardiac biomarkers high-sensitivity troponin I (hs-cTnI), myohemoglobin and creatine kinase-myocardial band (CK-MB) were assessed in all patients. The clinical outcomes were defined as hospital discharge or death. The median age of the study cohort was 55 (IQR, 46-65) years, and 102 (56.4%) were males. Forty-two of the 181 patients (23.2%) had cardiac injury. Old age, high leukocyte count, and high levels of aspartate transaminase (AST), D-dimer and serum ferritin were significantly associated with cardiac injury. Multivariate regression analysis revealed old age and elevated D-dimer levels as being strong risk predictors of in-hospital mortality. Interleukin 6 (IL6) levels were comparable in patients with or without cardiac injury. Serial observations of coagulation parameters demonstrated highly synchronous alterations of D-dimer along with progression to cardiac injury. Cardiac injury is a common complication of COVID-19 and is an independent risk factor for in-hospital mortality. Old age, high leukocyte count, and high levels of AST, D-dimer and serum ferritin are significantly associated with cardiac injury, whereas IL6 are not. Therefore, the pathogenesis of cardiac injury in COVID-19 may be primarily due to coagulation dysfunction along with microvascular injury.