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Updated: Nov 19, 2025
Dynamic Monitoring of Seroconversion using a Multianalyte Immunobead Assay for Covid-19
Published on: February 16, 2022
Comparison of clinical and serological features of RT-PCR positive and negative COVID-19 patients
Insights
Serological tests for COVID-19 (coronavirus disease 2019) can aid diagnosis when reverse transcriptase polymerase chain reaction (RT-PCR) is negative. Antibody detection timing is crucial for accurate COVID-19 assessment.
Area of Science:
- Virology
- Immunology
- Epidemiology
Background:
- The 2019 coronavirus disease (COVID-19) pandemic originated in Wuhan, China.
- Reverse transcriptase polymerase chain reaction (RT-PCR) is a primary diagnostic tool for COVID-19.
Purpose of the Study:
- To compare clinical and serological features of COVID-19 patients with positive and negative RT-PCR results.
- To evaluate the utility of serological assays in COVID-19 diagnosis.
Main Methods:
- Retrospective cohort study of 125 COVID-19 patients (9 February–4 April 2020).
- Analysis of demographic, clinical, and serological data (colloidal gold assay).
- Comparison between RT-PCR positive (87 cases) and RT-PCR negative (38 cases) groups.
Main Results:
- No significant differences in demographics, symptoms, complications, or treatments between RT-PCR positive and negative groups.
- High positivity rates for serum IgM/IgG in both groups (94% and 87%, respectively).
- Distinct detection windows: IgM detectable from day 3, IgG from day 10 post-symptom onset.
Conclusions:
- Serological tests are valuable auxiliary tools for COVID-19 diagnosis, especially when RT-PCR is negative.
- Optimal timing of serological testing relative to symptom onset is critical for accurate COVID-19 assessment.
Background:
In December 2019, an outbreak of coronavirus disease 2019 (COVID-19) began in Wuhan, China, and led to a global epidemic. We aimed to compare the clinical and serological features of COVID-19 patients with positive and negative reverse transcriptase polymerase chain reaction (RT-PCR) tests.
Methods:
This was a retrospective cohort study conducted from 9 February to 4 April 2020. COVID-19 patients at Leishenshan Hospital in Wuhan, China (125 total cases; 87 RT-PCR positive and 38 RT-PCR negative) were included. COVID-19 serology was assessed by colloidal gold assay. All cases were analyzed for demographic, clinical, and serological features.
Results:
There were no significant differences in most demographic features, clinical symptoms, complications or treatments of RT-PCR positive and negative COVID-19 patients. Serum IgM/IgG was positive in 82 (94%) and 33 (87%) RT-PCR positive and negative cases, respectively. IgM was detectable as early as 3 days after symptom onset and was undetectable 60 days after symptom onset. By contrast, IgG could be detected only 10 days after symptom onset and reached its peak 60 days after symptom onset.
Conclusions:
Serological tests performed during the appropriate time window of disease progression could be valuable auxiliary methods to RT-PCR in COVID-19 patients.
