The impact of COVID-19 epidemic phase and changes in mean viral loads: implications for SARS-CoV-2 testing strategies

Evaluating the value of anti-SARS-CoV-2 antibody detection and neutralizing responses with euvirus: A population of 10776 close contacts in the epidemic of Fujian

BACKGROUND

Nucleic acid detection represents limitations due to its false-negative rate and technical complexity in the COVID-19 pandemic. Anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody tests are widely spread all over the world presently. However, there is no report on the effectiveness of anti-SARS-CoV-2 antibody testing methods in China.

METHODS

We gathered 10776 serum samples from close contacts of the SARS-CoV-2 infections in Fujian of China and used 2 chemiluminescence immunoassays (Wantai Bio., Yahuilong Bio.) and 2 lateral flow immunoassays (Lizhu Bio. and Dongfang Bio.) to perform the anti-SARS-CoV-2 antibody tests in China.

RESULTS

The 4 antibody tests have great diagnostic value for infected or uninfected, especially in the neutralizing antibodies tests, the AUC can reach 0.939 (Wantai Bio.) and 0.916 (Yahuilong Bio.). Furthermore, we used pseudoviruses and euvirus neutralization assay to validate the effectiveness of these antibody test, the results of pseudoviruses neutralization assay or euvirus neutralization assay shows a considerable correlation with the 4 antibody detection respectively, particularly in euvirus neutralization assay, neutralizing antibodies detected by Wantai Bio. or Yahuilong Bio., the correlation can get the level of 0.93 or 0.82.

CONCLUSIONS

The findings of this study demonstrate that the detections of antibodies have profound value in the diagnosis of COVID-19.

Considerations regarding Interpretation of Positive SARS-CoV-2 Molecular Results with Late Cycle Threshold Values

COVID-19 disease lies on a spectrum, ranging from completely asymptomatic to mild disease to severe and critical disease. Studies have shown that prolonged shedding or sporadic detection of SARS-CoV-2 RNA can occur long after symptom resolution. Adding to these clinical complexities is the demand for testing for SARS-CoV-2 at all stages of diseases, frequently driven by screening of asymptomatic persons, something that traditionally has not been performed for other viral respiratory diseases. This can lead to positive results from nucleic acid amplification tests (NAATs), such as RT-PCR, with late cycle threshold (CT) values near the test’s limit of detection. In this commentary, we review unique attributes of COVID-19 and causes of NAAT late CT values. We provide interpretation considerations as well as strategies to aid in test interpretation.