AACC Publishes New COVID-19 Guidelines for Clinical Laboratories

The American Association for Clinical Chemistry (AACC; Washington, DC, USA) has released new guidance that offers answers on SARS-CoV-2 antibodies for clinical laboratorians amidst constant questions and emerging data about serologic testing.

As the COVID-19 pandemic evolved over the past year, so too did available antibody tests for SARS-CoV-2 and clinicians’ understanding of how to use them. In 2020, AACC had published initial recommendations about the use and limitations of serology testing but felt there was a need for a more in-depth guideline. This spring, the expert panel, including professionals from clinical chemistry, microbiology, and immunology laboratories, as well as specialists from in vitro diagnostics, industry, and regulatory agencies, released a document of practical recommendations for implementing and interpreting evolving SARS-CoV-2 emergency use authorization (EUA) and laboratory-developed test (LDT) serologic testing.

The document provides information about serologic assay design, antibody classes, and the kinetics of the humoral immune response, as well as verification and validation of both EUA and LDTs. It also discusses four indications for serologic testing: supporting the diagnosis of COVID-19 and related sequelae (e.g., multisystem inflammatory syndrome in children); identifying potential convalescent plasma donors and manufacturing of convalescent plasma; epidemiologic and seroprevalence studies; and vaccine efficacy studies.

Clinical laboratories can find multiple uses for the document. It could be a reference guide for understanding the host immune response to SARS-CoV-2, antibody kinetics, and available EUA assays; or it could help laboratorians understand the clinical utilities and limitations of serology testing and gain insights into the nuances in implementing EUA or LDT serology testing. Importantly, serology tests are not recommended for diagnostic purposes for SARS-CoV-2 infection. But they could identify different types of antibodies, such as IgG and IgM, and antibodies for S and N proteins or neutralizing antibodies. There are a lot of vaccine-preventable diseases for which laboratories perform serologic testing, although the key is first identifying a minimum antibody threshold or correlate of protective immunity for those pathogens.

“Though various organizations have published guidelines on clinical utilities of serology testing, ours is the first and most comprehensive document we know so far for the implementation of the tests, particularly EUA tests, in clinical laboratories,” said Y. Victoria Zhang, PhD, MBA, vice chair for clinical enterprise strategy and director of clinical chemistry for the University of Rochester Medical Center. “We wanted this guideline to be a reference for our own labs and trainees for implementing EUA and LDT serology tests in-house. It is our intention to provide a full reference for laboratory professionals and healthcare workers to appropriately implement these assays in the clinical laboratory and interpret the results to serve their patient needs during this pandemic.”

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