Abstract and Introduction
Antibody testing for SARS-CoV-2 has been established as a tool with broad utility in the surveillance and control of the COVID-19 pandemic. However, because of limited knowledge about the duration of humoral immunity to COVID-19 and the existence of unique individual immune responses, the potential role of antibody testing in the diagnosis of current and past infections of COVID-19 remains ambiguous. Herein, we describe a unique case of an asymptomatic patient showing a persistent positive total antibody test for SARS-CoV-2 while testing negative for SARS-CoV-2 RNA and IgG-specific antibodies. This case study shows how a combination of tests can be employed to identify a false positive and draw conclusions about a patient's COVID-19 status. It also highlights the complexity of using antibody testing for the diagnosis of COVID-19.
The infectious disease COVID-19, caused by SARS-CoV-2, has spread rapidly around the world, causing a pandemic. Many recent studies have focused on the utility of SARS-CoV-2 antibody testing for identifying current and past infections.[1,2] In addition, antibody testing has been explored as a tool for obtaining information on the stage of disease progression,[2–4] for identifying undiagnosed infections past the point of viral shedding,[5,6] and as a promising option for monitoring the portion of a population previously infected.[7,8] However, despite the development of tests offering high levels of sensitivity and specificity for SARS-CoV-2 antibodies, many limitations exist for these potential uses. These include a lack of knowledge of the duration of SARS-CoV-2 antibodies after infection and the impact of low population seroprevalence on the ability to make accurate predictions using antibody testing. In addition to these limitations, multiple unique cases have been reported that illustrate the complexity and lack of clarity of the role that antibody tests should play in diagnosing COVID-19 infection.[6,11] Additional research is needed to explore the factors that influence antibody test accuracy and to clarify how to manage patients in whom the test results do not give a straightforward answer. Here, we report a unique case of a patient with no evidence of current or past infection with COVID-19 who persistently tested positive for SARS-CoV-2 antibodies on 1 test while testing negative on another.
Lab Med. 2022;53(1):e1-e3. © 2022 American Society for Clinical Pathology