SARS-CoV-2 seroprevalence in asymptomatic or mild symptomatic people and symptomatic patients with negative PCR results: The hidden perspective in epidemiological reports

  1. Nazila Hajiahmadi
  2. Faezeh Mojtahedzadeh
  3. Atefeh Yari
  4. Mahdi Tat
  5. Hoorieh Soleimanjahi
  6. Saeid Amel Jamehdar
  7. Mitra Jafari
  8. Samira Asli
  9. Rohollah Dorostkar
  10. Maryam Nazemipour
  11. Mohammad Ali Mansournia
  12. Taravat Bamdad

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Abstract

Background

SARS-CoV-2 has led to the current pandemic of respiratory disease. The reports of confirmed COVID-19 cases based on molecular tests do not completely cover the total number of infected people. These reports do not include the asymptomatic or mildly symptomatic patients and also the patients with false-negative RT-PCR results, while the infection is contagious in all of these conditions.

Objective

In this study, we tried to improve our conception of the hidden perspective of SARS-CoV-2 in epidemiological reports.

Methods

From May 30 to June 17, 2020, blood samples were collected from two groups of people: asymptomatic or mild symptomatic volunteer participants and severe symptomatic hospitalized patients with negative PCR results. Detection of SARS-CoV-2 antibody was done with ELISA kit targeting N or S proteins.

Results

Totally 716 samples from volunteer participants and 81 samples from symptomatic hospitalized patients with negative PCR were evaluated. The test performance-adjusted seroprevalence (95% CI) of SARS-CoV-2 anti-N IgG was 17.3% (8.8%, 25.8%) for volunteers and 25.5% (12.8%, 39.7%) for anti-N and S IgM in hospitalized group. There was an association between high-risk occupations, high-risk behaviors, or symptomatic diseases with positive SARA-Cov-2 N antibody results. Among anti-N positive infected individuals, 49.2% (21.4%, 78.8%) were anti-S positive.

Conclusion

The results showed that SARS-COV-2 infection occurs in asymptomatic or mildly symptomatic individuals, but in more than half of them, the produced antibody is not protective. Findings of hospitalized patients also showed that the combination of IgM assay with real-time PCR improves the detection of the disease by more than 25% in negative molecular cases.

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  1. ScreenIT

    SciScore for 10.1101/2021.07.11.21260336: (What is this?)

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

    Table 1: Rigor

    EthicsConsent: Written informed consents were obtained before sampling and each volunteer was asked to answer a questionnaire form including demographic data such as age, gender, occupation, high-risk behaviors, and history of symptoms compatible with COVID-19 from February 2020.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Anti-N IgG SARS-CoV-2 antibody ELISA kit with 94.1% sensitivity and 98.3% specificity and anti-S IgG kit with 85.3% sensitivity and 99.01 % specificity was used for samples of volunteer participants.
    Anti-N IgG SARS-CoV-2
    suggested: None
    anti-S IgG
    suggested: None
    IgM SARS-CoV-2 antibody ELISA kit coated with N and S proteins with 79.4% sensitivity and 97.3% specificity was used for samples of hospitalized patients with negative PCR results.
    IgM SARS-CoV-2
    suggested: (Bethyl Cat# E88-302, RRID:AB_2892019)
    Software and Algorithms
    SentencesResources
    All analyses were performed in Stata version 14 (Stata, https://www.stata.com/).
    https://www.stata.com/
    suggested: (COLELMS: Stata module to calculate Coles LMS values for growth data, RRID:SCR_007244)

    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:
    This study had several limitations such as the limited number of participants in each study group which reduced the chance of randomized sampling. In addition, collecting the information of COVID-19 related symptoms was through self-reporting. Besides, the newly infected people without seroconversion have been missed as well as probable false-positive results due to the cross-reactivity of the serological test with other coronaviruses. In conclusion, the obtained results revealed the existence of virus spreading risk among the cases without confirmed symptoms or molecular tests, but these infected individuals may not produce protective antibodies. The results of this study reflect the Ab status of the population only at the sampling time and due to the variability of recent epidemic conditions in the community, continuous studies in this field are necessary to clarify the situation and extent of COVID-19 in society.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    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.

    Results from scite Reference Check: We found no unreliable references.

    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 10.1101/2021.07.11.21260336v1 on medRxiv