Viral Kinetics and Antibody Responses in Patients with COVID-19

  1. Wenting Tan
  2. Yanqiu Lu
  3. Juan Zhang
  4. Jing Wang
  5. Yunjie Dan
  6. Zhaoxia Tan
  7. Xiaoqing He
  8. Chunfang Qian
  9. Qiangzhong Sun
  10. Qingli Hu
  11. Honglan Liu
  12. Sikuan Ye
  13. Xiaomei Xiang
  14. Yi Zhou
  15. Wei Zhang
  16. Yanzhi Guo
  17. Xiu-Hua Wang
  18. Weiwei He
  19. Xing Wan
  20. Fengming Sun
  21. Quanfang Wei
  22. Cong Chen
  23. Guangqiang Pan
  24. Jie Xia
  25. Qing Mao
  26. Yaokai Chen
  27. Guohong Deng

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Abstract

Background

A pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been spreading over the world. However, the viral dynamics, host serologic responses, and their associations with clinical manifestations, have not been well described in prospective cohort.

Methods

We conducted a prospective cohort and enrolled 67 COVID-19 patients admitting between Jan 26 and Feb 5, 2020. Clinical specimens including nasopharyngeal swab, sputum, blood, urine and stool were tested periodically according to standardized case report form with final follow-up on February 27. The routes and duration of viral shedding, antibody response, and their associations with disease severity and clinical manifestations were systematically evaluated. Coronaviral particles in clinical specimens were observed by transmission electron microscopy (TEM).

Results

The median duration of SARS-CoV-2 RNA shedding were 12 (3-38), 19 (5-37), and 18 (7-26) days in nasopharyngeal swabs, sputum and stools, respectively. Only 13 urines (5.6%) and 12 plasmas (5.7%) were viral positive. Prolonged viral shedding was observed in severe patients than that of non-severe patients. Cough but not fever, aligned with viral shedding in clinical respiratory specimens, meanwhile the positive stool-RNA appeared to align with the proportion who concurrently had cough and sputum production, but not diarrhea. Typical coronaviral particles could be found directly in sputum by TEM. The anti-nucleocapsid-protein IgM started on day 7 and positive rate peaked on day 28, while that of IgG was on day 10 and day 49 after illness onset. IgM and IgG appear earlier, and their titers are significantly higher in severe patients than non-severe patients ( p <0.05). The weak responders for IgG had a significantly higher viral clearance rate than that of strong responders ( p = 0.011).

Conclusions

Nasopharyngeal, sputum and stools rather than blood and urine, were the major shedding routes for SARS-CoV-2, and meanwhile sputum had a prolonged viral shedding. Symptom cough seems to be aligned with viral shedding in clinical respiratory and fecal specimens. Stronger antibody response was associated with delayed viral clearance and disease severity.

Summary boxes

What is already known on this topic

As a newly appearing infectious disease, early efforts have focused on virus identification, describing the epidemiologic characteristics, clinical course, prognostics for critically illed cases and mortality. Among COVID-19 cases reported in mainland China (72 314 cases, updated through February 11, 2020), 81% are mild, 14% are severe, and 5% are critical. The estimated overall case fatality rate (CFR) is 2.3%.

Some case series reported had shown that SARS-CoV-2 could shed in upper/lower respiratory specimens, stools, blood and urines of patients. However, important knowledge gaps remain, particularly regarding full kinetics of viral shedding and host serologic responses in association with clinical manifestations and host factors.

What this study adds

The incubation period has no change after spreading out of Wuhan, and has no sex or age differences, however, children had prolonged incubation period. Due to early recognition and intervention, COVID-19 illness of Chongqing cohort is milder than that of Wuhan patients reported.

This prospective cohort study on SARS-CoV-2 infection shows clearly that the viral and serological kinetics were related in duration of infection, disease severity, and clinical manifestations of COVID-19. Our data demonstrate that nasopharyngeal, sputum and stools are major shedding routes for SARS-CoV-2, and stronger NP antibody response is associated with delayed viral clearance and disease severity.

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  1. ScreenIT

    SciScore for 10.1101/2020.03.24.20042382: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board StatementIRB: This study was approved by the ethics committee of CPHMC (document no. 2020-002-01-KY, 2020-003-01-KY) and conducted in accordance with Declaration of Helsinki principles.
    Consent: Written informed consent was obtained from each subject.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Serological Assays: Serum specific IgM and IgG antibodies were analyzed by ELISA kits (Livzon Diagnostics Inc., Zhuhai, China), which using SARS-CoV-2 nucleocapsid protein (NP) as antigen, following the instruction manual.
    IgG
    suggested: None
    SARS-CoV-2 nucleocapsid protein (NP
    suggested: None
    Software and Algorithms
    SentencesResources
    Statistical analyses were done using the SPSS software (v13.0) and GraphPad Prism (v5.0).
    SPSS
    suggested: (SPSS, RRID:SCR_002865)
    GraphPad
    suggested: (GraphPad Prism, RRID:SCR_002798)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    Nevertheless, there are some limitations for our study. First, large-scale, multi-center cohorts from other regions are needed to verify our preliminary findings. Second, the viability of virus in stools, plasma and urine, and its role in pathogenesis or transmission need to be clarified. Third, antibodies to spike and envelope proteins, and their role for protection for SARS-CoV-2 infection or reinfection are still unknown and waiting for future investigations.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We found bar graphs of continuous data. We recommend replacing bar graphs with more informative graphics, as many different datasets can lead to the same bar graph. The actual data may suggest different conclusions from the summary statistics. For more information, please see Weissgerber et al (2015).

    Results from JetFighter: Please consider improving the rainbow (“jet”) colormap(s) used on page 27. At least one figure is not accessible to readers with colorblindness and/or is not true to the data, i.e. not perceptually uniform.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  2. Version published to 10.1101/2020.03.24.20042382v1 on medRxiv