However, the time has come to reopen the clinics and operating theaters to resume transplant activity. In order to do this safely, the development of new diagnostic tools is required to enable the transplant laboratory to assess the risk of SARS-CoV-2, the underlying disease of COVID-19. Current data shows the mortality rate among transplant recipients who test positive for COVID-19 can be as high as 32%².

Consider the body of evidence currently available that indicates how active infectious episodes can result in profound changes to the patients’ HLA antibody profile³. While the exact mechanisms that underpin these processes remain controversial, the emerging consensus is that pathogenic viral infections, such as COVID-19, may trigger an anamnestic B-cell response. Such memory responses can result in an increase in both the breadth and strength of the HLA antibody response⁴.

Additionally, the current mass mobilization of the scientific community for the development of a safe and effective COVID-19 vaccine may pose additional challenges for transplant patients. Data has indicated that vaccine administration also has the potential to induce changes in the HLA antibody repertoire of our transplant patients^5,6. By monitoring antibody responses post COVID-19 vaccination, we can detect changes and, if transplant eligibility or existing graft health is impacted, better manage the associated risk factors for these conditions.

In order to fully understand a patient’s risk factor, transplant teams need be able to characterize the immune response to COVID-19 by simultaneously detecting the response to the spike protein, receptor-binding domain, nucleocapsid and other SARS-CoV-2 proteins.

Solution

Viral- and vaccination-induced changes to HLA sensitization status can have a profound impact on both transplant waitlist candidates and on those looking to preserve function in their transplanted organ. In response to this unmet patient need, we have developed the LABScreen COVID Plus assay, a comprehensive SARS-CoV-2 specific antibody detection panel that takes advantage of the multiplex capability off ered by the Luminex platform. It can be run in parallel with conventional LABScreen products to give the full picture of a patients’ HLA and COVID antibody status.

By uniquely targeting multiple subunits of the extracellular domain (commonly referred to as the “spike” protein) as well as the internal nucleocapsid protein, the LABScreen COVID Plus assay provides a reliable detection system (Fig. 1). The kinetics of the antibody response to SARS-CoV-2 are now reasonably well described with antibodies being routinely detected within 7-14 days after the onset of symptoms7. The added specificity of the LABScreen COVID Plus assay takes on greater importance since recent studies have indicated that individuals who develop antibodies to the viral nucleocapsid suff er increased mortality compared to those whose humoral response is limited to the recognition of spike protein8. In contrast, studies have indicated that the antibodies to the spike subunits RBD and S1 may have a neutralizing eff ect9 (Fig. 2). The benefit of the antibody to Spike S2 is unknown, although detection of the Spike S2 antibody would indicate exposure to COVID-19. Clinical relevance of antibodies to Spike S2 may be established with future studies.

Furthermore, the panel for LABScreen COVID Plus includes specific targets for the common cold coronavirus families and markers for Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS), thereby reducing the possibility that cross-reactive viral response may give rise to false positive COVID-19 tests.