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As the COVID-19 epidemic is still ongoing, a more rapid detection of SARS-CoV-2 infection such as viral antigen-detection needs to be evaluated for early diagnosis of COVID-19 disease. Here, we report the dynamic changes of SARS-CoV-2 viral antigens in nasopharyngeal swabs of COVID-19 patients and its association with the viral nucleic acid clearance and clinical outcomes. Eighty-five COVID-19 patients were enrolled for detection of SARS-CoV-2 viral antigens, including 57 anti-SARS-CoV-2 antibody negative cases and 28 antibody positive cases. The viral antigen could be detected in 52.63% (30/57) patients with SARS-CoV-2 antibody negative at the early stage of SARS-CoV-2 infection, especially in the first 5 days after disease onset (p = 0.0018) and disappeared in about 8 days after disease onset. Viral antigens were highly detectable in patients with low Ct value (less than 30) of SARS-CoV-2 nucleic acid RT-PCT assay, suggesting the expression of viral antigen was associated with high viral load. Furthermore, positive antigen detection indicated disease progression, nine cases with positive antigen (9/30, 30.0%), in contrast to two cases (2/27, 7.40%) (p = 0.0444) with negative antigen, which progressed into severe disease. Thus, the viral antigens were persistent in early stages of infection when virus was in highly replicating status, and viral antigen detection promises to rapidly screen positive patients in the early stage of SARS-CoV-2 infection.

T cells play a critical role in coronavirus diseases. How they do so in COVID-19 may be revealed by analyzing the epigenetic chromatin accessibility of cis- and trans-regulatory elements and creating transcriptomic immune profiles. We performed single-cell assay for transposase-accessible chromatin (scATAC) and single-cell RNA (scRNA) sequencing (seq) on the peripheral blood mononuclear cells (PBMCs) of severely ill/critical patients (SCPs) infected with COVID-19, moderate patients (MPs), and healthy volunteer controls (HCs). About 76,570 and 107,862 single cells were used, respectively, for analyzing the characteristics of chromatin accessibility and transcriptomic immune profiles by the application of scATAC-seq (nine cases) and scRNA-seq (15 cases). The scATAC-seq detected 28,535 different peaks in the three groups; among these peaks, 41.6 and 10.7% were located in the promoter and enhancer regions, respectively. Compared to HCs, among the peak-located genes in the total T cells and its subsets, CD4 + T and CD8 + T cells, from SCPs and MPs were enriched with inflammatory pathways, such as mitogen-activated protein kinase (MAPK) signaling pathway and tumor necrosis factor (TNF) signaling pathway. The motifs of TBX21 were less accessible in the CD4 + T cells of SCPs compared with those in MPs. Furthermore, the scRNA-seq showed that the proportion of T cells, especially the CD4 + T cells, was decreased in SCPs and MPs compared with those in HCs. Transcriptomic results revealed that histone-related genes, and inflammatory genes, such as NFKBIA, S100A9, and PIK3R1, were highly expressed in the total T cells, CD4 + T and CD8 + T cells, both in the cases of SCPs and MPs. In the CD4 + T cells, decreased T helper-1 (Th1) cells were observed in SCPs and MPs. In the CD8 + T cells, activation markers, such as CD69 and HLA class II genes (HLA-DRA, HLA-DRB1, and HLA-DRB5), were significantly upregulated in SCPs. An integrated analysis of the data from scATAC-seq and scRNA-seq showed some consistency between the approaches. Cumulatively, we have generated a landscape of chromatin epigenetic status and transcriptomic immune profiles of T cells in patients with COVID-19. This has provided a deeper dissection of the characteristics of the T cells involved at a higher resolution than from previously obtained data merely by the scRNA-seq analysis. Our data led us to suggest that the T-cell inflammatory states accompanied with defective functions in the CD4 + T cells of SCPs may be the key factors for determining the pathogenesis of and recovery from COVID-19., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Li, Wu, Ling, Guo, Qin, Ren, Wang, Yang, Chen, Liao, Liu, Peng, Xu, Wang, Shen, Chen, Liu, Niu, Zhu, Liu, Li, Zhu, Zhu, Zhou and Lu.)

To evaluate the effect of Nirmatrelvir‐ritonavir therapy and coronavirus disease 2019 (COVID‐19) vaccination on clinical outcomes of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) Omicron infection, we retrospectively analyzed the clinical data of 762 adult patients with confirmed Omicron BA2.2 variant infection, of them 488 patients received standard therapy and 274 patients received Nirmatrelvir‐ritonavir therapy. Subjects were matched by propensity score matching using R language, the baseline factors were balanced by the nearest‐neighbor matching method and were compared, together with the factors including progression to severe/critical disease, viral clearance time, length of hospital stay, and virological rebound of SARS‐CoV‐2 infection. Nirmatrelvir‐ritonavir therapy significantly accelerated viral clearance at Days 14 and 28 during hospitalization, but it had no impact on disease progression, length of hospital stay, or infection rebound. In contrast, COVID‐19 vaccination before admission was positively correlated with the viral clearance rate and negatively correlated with disease progression in a dose‐dependent way. COVID‐19 vaccination reduced the probability of infection rebound. Other factors such as the number of comorbidities, pneumonia on‐admission, and high D2 levels were positively correlated with disease progression. Our study strongly recommended booster COVID‐19 vaccination for the elderly population, particularly patients with comorbidities to prevent critical disease. [ABSTRACT FROM AUTHOR]