Serologic testing provides a surveillance strategy for the fight against COVID-19

November 10, 2020 Categories: ACLA Blog

Since the start of this public health crisis, ACLA member laboratories have developed and expanded a range of tests and methods to support patients – including the first at-home specimen collection kits, COVID-19 specimen pooling and the launch of novel RNA extraction methods. Separate from tests used to determine an active infection, the use of serologic or antibody testing analyzes a patients’ blood specimen for the presence of immune response proteins developed due to a viral exposure or infection. In addition to its use in developing therapeutics and as a vital tool in vaccine trials, widespread serologic testing helps experts determine the number of individuals exposed or infected with COVID-19. Also, it provides valuable information to support broader prevention, containment and mitigation strategies.

Specifically, serologic testing is a valuable surveillance tool to help public health experts learn about the level of exposure to a virus in a community. Serologic testing can also be a critical asset in determining resource allocation and public health interventions’ effectiveness in a pandemic. While we continue to study the science around the exact level or the duration of immunity against reinfection that SARS-CoV-2 antibodies may provide, we know that accurate and reliable serologic testing is fundamental to our national response efforts.  

In July, researchers from Ascend Clinical, an ACLA member laboratory specializing in testing services for kidney disease, began collaborating with the Stanford University School of Medicine to understand the seroprevalence – the number of individuals who test positive for a certain disease – of SARS-CoV-2 antibodies across large populations. While the study focused specifically on patients receiving dialysis treatment, many of its findings have significant implications for the general population. 

Researchers collected information from more than 28,000 randomly selected dialysis patients from across the United States. Ascend Clinical performed testing using the Siemens Atellica IM SARS-CoV-2 Total (COV2T) antibody assay and discovered that there were higher rates of SARS-CoV-2 antibodies in Black and Hispanic patients as well as those living in densely populated areas. The study also found significant regional variation – from less than 5 percent in the West to greater than 25 percent in the Northeast.

As of July, researchers from Ascend and Stanford estimated that fewer than 10 percent of U.S. adults possessed SARS-CoV-2 antibodies – a figure well below what experts say is necessary for herd immunity. The dialysis population may be ideal for studying the general spread of COVID-19 in the U.S. because these patients undergo monthly, routine blood draws and represent other similar COVID-19 risk factors. As the COVID-19 pandemic continues, applying these findings and the results from serologic testing to bolster our surveillance efforts can help tailor public health strategies and meet the needs of the most vulnerable communities impacted by COVID-19.

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