Characteristics and assessment of the usefulness of serological tests in the diagnostic of infections caused by coronavirus SARS-CoV-2 on the basis of available manufacturer’s data and literature review

Abstract

Recognized in 2019 in Wuhan, China, the new SARS-CoV-2 coronavirus is responsible for the occurrence of a global pandemic disease called COVID-19. So far, confirmation of infection is based on the detection of virus RNA in a sample taken from a person meeting the suspected case definition. However, in the laboratory diagnosis of SARS-CoV-2 infections, in addition to genetic tests, serological methods can also be used to detect specific antibodies of the IgM, IgG and IgA class produced after contact with antigens or to detect viral antigen. Currently, a number of rapid immunochromatographic, chemiluminescent and ELISA immunoassay tests developed by different manufacturers for the diagnosis of COVID-19 are available on the market. Despite this fact, so far there is no WHO or ECDC recommendations or even reliable research regarding the usefulness of serological investigations in the laboratory diagnosis of infections caused by SARS-CoV-2.

Update on serologic testing in COVID–19

“…However, due to the limited sensitivity and specificity of this assay, the results often require validation. In the case of COVID–19, a molecular test has the highest specificity up to 7 days after contact with the pathogen [3] . After the first week, the number of truly positive results decreases, and the number of false-negative outcomes increases [3] .…”

“…In the case of COVID–19, a molecular test has the highest specificity up to 7 days after contact with the pathogen [3] . After the first week, the number of truly positive results decreases, and the number of false-negative outcomes increases [3] . Additionally, the collection site may interfere with the results.…”

“…False–positive outcomes may result from cross–reactions, as well as sample pollution in the laboratory [8] . Moreover, a molecular test result may be unreliable due to untimely collection of the sample, insufficient sample size, virus mutation, or limited replication phase in the host cells [2] , [3] . Further limitations involve technical challenges with the analysis, the requirement for adequately prepared and certified laboratory including laboratory personnel, and fairly long waiting time for the results [2] , [5] .…”

“…Specific anti–SARS–CoV–2 serum antibodies have garnered much attention due to their high diagnostic potential. The data indicate that the virus–specific antibodies may serve as a diagnostic tool to increase the sensitivity of molecular tests as well as assist in controlling the spread of the infection in a population [3] .…”

The Challenges of Contact Tracing in a Case of Early Neonatal Sepsis with COVID-19

“…All results were negative. The sensitivity of the test was 77.1% and 74.3% for IgM and IgG, respectively [1]. The antibody response is closely related to disease severity; many asymptomatic people may have low antibody titers, which is inadequate for obtaining positivity on tests [2].…”