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Updated: Aug 19, 2025
Dynamic Monitoring of Seroconversion using a Multianalyte Immunobead Assay for Covid-19
Published on: February 16, 2022
Unspecific reactivity must be excluded in COVID-19 epidemiological analyses or virus tracing based on serologic
Min-Jing Cai1,2, Jie Lin1,2, Jian-Hui Zhu1,2
1Centre of Clinical Laboratory, Zhongshan Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China.
Insights
Unspecific reactivity in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody tests occurs in 0.361% of cases and is more common in adults. This finding is crucial for accurate COVID-19 epidemiological analysis.
Area of Science:
- Immunology
- Infectious Diseases
- Epidemiology
Background:
- Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19.
- Serologic testing is a key method for identifying SARS-CoV-2 infections.
- Evaluating unspecific reactivity in serologic tests is essential for accurate diagnosis.
Purpose of the Study:
- To determine the incidence and characteristics of unspecific reactivity in SARS-CoV-2 antibody tests.
- To compare unspecific reactivity in pre-pandemic and post-pandemic samples.
- To identify factors associated with unspecific reactivity.
Main Methods:
- Retrospective analysis of 46,777 post-pandemic samples for anti-SARS-CoV-2 antibodies.
- Analysis of 1,114 pre-pandemic samples for comparison.
- Statistical analysis to evaluate incidence, characteristics, and associated factors.
Main Results:
- The incidence of unspecific reactivity was 0.361% in post-pandemic samples, similar to pre-pandemic levels (0.359%).
- Adults (≥19 years) had a significantly higher probability of unspecific reactivity compared to younger individuals.
- Unspecific reactivity was associated with 14 disease categories, notably skin, respiratory, and neoplasm diseases.
Conclusions:
- Unspecific reactivity occurs at a low but consistent rate (0.361%) across various disease categories.
- The incidence of unspecific reactivity did not significantly differ between pre- and post-pandemic periods.
- Excluding unspecific reactivity is vital for reliable COVID-19 epidemiological studies and virus tracing.
Background:
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19). Serologic testing is complementary to nucleic acid screening to identify SARS-CoV-2. This study aimed to evaluate unspecific reactivity in SARS-CoV-2 serologic tests.
Materials And Methods:
Total anti-SARS-CoV-2 antibodies from 46,777 subjects who were screened for SARS-CoV-2 were retrospectively studied to evaluate the incidence and characteristics of the unspecific reactivity. A total of 1,114 pre-pandemic samples were also analysed to compare unspecific reactivity.
Results:
The incidence of unspecific reactivity in anti-SARS-CoV-2 total antibody testing was 0.361% in 46,777 post-pandemic samples, similar to the incidence of 0.359% (4/1,114) in 1,114 pre-pandemic samples (p = 0.990). Subjects ≥ 19 years old had a 2.753-fold [95% confidence interval (CI), 1.130-6.706] higher probability of unspecific reactivity than subjects < 19 years old (p = 0.026). There was no significant difference between the sexes. The unspecific reactivity was associated with 14 categories within the disease spectrum, with three tops being the skin and subcutaneous tissue diseases (0.93%), respiratory system diseases (0.78%) and neoplasms diseases (0.76%). The percentage of patients with a titer ≥ 13.87 cut-off index (COI) in the unspecific reactivity was 7.69%.
Conclusion:
Our results suggest a unspecific reactivity incidence rate of 0.361% involving 14 categories on the disease spectrum. Unspecific reactivity needs to be excluded when performing serologic antibody testing in COVID-19 epidemiological analyses or virus tracing.
