Diagnostic performance of commercially available COVID-19 serology tests in Brazil

https://doi.org/10.1016/j.ijid.2020.10.008Get rights and content
Under a Creative Commons license
open access

Highlights

  • The performance of SARS-CoV-2 serological tests remains markedly low until the 14th day of symptoms, and their use is not recommended at this stage.

  • The performance of SARS-CoV-2 serological tests increases with the duration of symptoms and the clinical severity of the disease.

  • In general, IgM and IgA antibodies are not earlier or more sensitive markers for SARS-CoV-2 diagnosis, reaching their highest positivity rate after 14 days of the onset of symptoms.

  • LFIA tests are more specific than ELISA tests for SARS-CoV-2 diagnosis.

  • Infectious diseases prevalent in tropical regions, such as HIV, leishmaniasis, arbovirus, and malaria, may be linked to false-positive results in SARS-CoV-2 tests.

Abstract

Timely and accurate laboratory testing is essential for managing the global COVID-19 pandemic. Reverse transcription polymerase chain reaction remains the gold-standard for SARS-CoV-2 diagnosis, but several practical issues limit the test’s use. Immunoassays have been indicated as an alternative for individual and mass testing. Objectives: To access the performance of 12 serological tests for COVID-19 diagnosis.

Methods

We conducted a blind evaluation of six lateral-flow immunoassays (LFIAs) and six enzyme-linked immunosorbent assays (ELISAs) commercially available in Brazil for detecting anti-SARS-CoV-2 antibodies.

Results

Considering patients with seven or more days of symptoms, the sensitivity ranged from 59.5% to 83.1% for LFIAs and from 50.7% to 92.6% for ELISAs. For both methods, the sensitivity increased with clinical severity and days of symptoms. The agreement among LFIAs performed with digital blood and serum was moderate. Specificity was, in general, higher for LFIAs than for ELISAs. Infectious diseases prevalent in the tropics, such as HIV, leishmaniasis, arboviruses, and malaria, represent conditions with the potential to cause false-positive results with these tests, which significantly compromises their specificity.

Conclusion

The performance of immunoassays was only moderate, affected by the duration and clinical severity of the disease. Absence of discriminatory power between IgM/IgA and IgG has also been demonstrated, which prevents the use of acute-phase antibodies for decisions on social isolation.

Keywords

Antibody
COVID-19
Performance
SARS-CoV-2
Rapid test
Serology
Diagnosis
Accuracy

Cited by (0)