Clinical Application of Serologic Testing for Coronavirus Disease 2019 in Contemporary Cardiovascular Practice

Abstract

In patients with cardiovascular disease, the use of antibody or serological testing is frequently encountered as the coronavirus disease 2019 pandemic continues to evolve. Antibody testing detects one form of the acquired immunological response to a pathogenic antigen. Once the immune system recognizes a viral antigen or a protein as foreign, a humoral immune response is initiated, which is generally detected by laboratory testing in 5 to 10 days after the initial exposure. While this information is critical from a public health perspective to implement surveillance systems and measures to limit infectivity and transmission rate, the misinterpretation of serologic testing in clinical practice has generated much confusion in the medical community because some attempted to apply these strategies to individual patient's treatment schemes. In this mini-review, we examine the different serologic-based testing strategies, how to interpret their results, and their public health impact at the population level, which are critical to contain the transmission of the virus in the community within a busy cardiovascular practice. Further, this review will also be particularly helpful as vaccination and immune therapy for coronavirus disease 2019 become available to the society as a whole.

Keywords: COVID‐19; cardiovascular diseases; immunity; serologic test.

Figure 1. Serology‐based testing to SARS‐COV‐2.

The figure illustrates the protein antigens of the severe acute respiratory syndrome coronavirus 2: nucleocapsid phosphoprotein, spike full‐length protein, and receptor binding domain and the 2 most common serology‐based testing strategies: enzyme‐linked immunosorbent assay and chemiluminescent immunoassay. PRNT₅₀ indicates 50% plaque reduction neutralization test; and SARS‐COV‐2, severe acute respiratory syndrome coronavirus 2. The nucleocapsid protein is not shown in the illustration because it is attached to the viral RNA. The illustration only shows the surface proteins; the orange proteins represent the phospholipid bilayer. The blue/purple 5‐part proteins represent viroporin pentamers, also called E proteins.

Figure 2. Positive predictive value for 2 testing strategies by prevalence of COVID‐19 in a hypothetical situation.

COVID‐19 indicates coronavirus disease 2019. Data derived from https://www.cdc.gov/coronavirus/2019‐ncov/lab/resources/antibody‐tests‐guidelines.html/.