Dr. Sarah Wheeler

Hi, my name is Sarah Wheeler. I work at the University of Pittsburgh Medical Center and the University of Pittsburgh. I am a medical director for the Automated Testing Laboratories at UPMC Children's Hospital as well as UPMC Mercy Hospital. I'm also associate medical director for Clinical Immunopathology.

Antibody testing is very important as part of infectious disease testing and control and, specifically with SARS-CoV-2, there is so much that we still don't understand about the disease.

Antibody testing has played and will continue to play an important role. For convalescent plasma donation, we definitely need to know if these patients have have mounted an antibody response or not before we accept them for convalescent plasma donation.

Additionally, there are nonstandard presentations where we suspect that the pathology we're seeing may be due to SARS-CoV-2 but the patient is RNA-negative, perhaps because their disease has migrated from their nasal passages into their lower respiratory system, in which case serology is very important for us to correctly identify the pathogen that's involved there.

Additionally, in managing the pandemic, epidemiology is really important, and serology gives us a key to being able to assess overall disease burden across the world when we have limitations in RNA testing and in getting people timely RNA testing.

So, this testing is very important for clinicians for a couple of reasons. First of all, nucleic acid testing or RT-PCR, detecting the RNA that's involved with the virus, allows us to detect the infection within a pretty narrow window. Some patients will continue to shed virus for weeks independent of if they are or not contagious. Other patients will only have their RNA be detectable for a short amount of time. /

Serology gives us the ability to look at a longer and larger window. Serology is an important component to RT-PCR. When patients come in that have had symptoms for a reasonably extended period of time, it's unclear if they're still contagious or where in their disease course they are.

So, if we're detecting them RNA-positive but still antibody-negative, they're likely still early in their disease course and there are early interventions that would be appropriate for these patients. Patients who are RNA-negative but serology-positive are a bit later in their disease course. So, there are other interventions that may be more appropriate.

One of the platforms we assessed was the Siemens Total SARS-CoV-2 Antibody assay and that platform allows for antigen in the capture phase as well as in the detection phase, which give us increased specificity.

We're using it as part of our orthogonal testing algorithm for all patient specimens that come through. Using this orthogonal testing algorithm has allowed us to ensure that we're not getting too many false positives in this kind of low-prevalence setting that we are currently in (and hopefully will continue to be in).

Serology testing for SARS-CoV-2 has been under a microscope. We have characterized the serology assays as they've come on the market in a way that we've not done with many infectious disease serology assays in a very long time. That's allowed us to tease out weaknesses as well as assess different applications that we have not really used for serology assays, particularly in respiratory illnesses.

As our understanding of serology is increasing, the importance of understanding the effects of past SARS-CoV-2 infection is going to be increasing. We still don't really understand what long-term effects we may have from SARS-CoV-2 infection. We know that viral infections can increase incidents of autoimmunity in patients. So, being able to serologically detect past infections is going to be of increased importance as we begin to see the downstream pathologies that may be coming from this respiratory virus.