Why Are COVID Antibody Tests Of Questionable Relevance Being Marketed To The Public?

It started mid-March with the sensation that I had cut one of my knuckles. Within two weeks, several fingers were swollen like sausages, and my fingertips had developed painful, burning spots. Soon thereafter, my husband noted one red, swollen toe. We are both emergency physicians, but we could not understand what was causing the symptoms, and it was not until a month later that we started to see COVID fingers and toes creeping into the news. The burning sensation continued, and I was referred for a broad panel of labs, all of which came back normal, including – curiously – my COVID antibody test. I communicated with my primary care doctor, a dermatologist, and an infectious disease specialist, all of whom concluded I had “COVID fingers.” If I had had the virus in March, why was my antibody test negative?

Ideally, after exposure to a foreign substance – like a virus – our antibodies provide protection against future exposures to that same biologic material. Recently, though, studies have begun to show that the predictability of commercial testing for COVID antibodies may be weaker than previously thought. One problem might be that some patients have antibodies present but at levels lower than commercial laboratories’ thresholds for detection. An alternative might be a true absence of the antibodies: A Chinese study in Nature Medicine reported that 40% of asymptomatic COVID-19 patients were seronegative for IgG – the most common antibody found in our blood – during the early convalescent phase of the disease. (The antibody levels dropped further as time went on.) There are also questions about whether commercial laboratories are targeting the most relevant antibodies in favor of detecting easier targets that are less clinically useful.

It is also possible that COVID antibodies are less important than we think in providing immunity to the virus: One study found that cellular immunity – the protection we get from T cells – may play a big role in COVID recovery. Recently Dr. Fauci indicated that, for COVID, T cell immunity might have a degree of memory that goes beyond the presence of antibodies.

In addition to whether negative antibody testing truly demonstrates that someone has been spared from COVID, commercial antibody testing has been criticized for the converse: A positive test may reflect immunity to other related coronaviruses responsible for the common cold, for example, instead of the novel coronavirus that causes COVID. In our collective fervor to develop COVID antibody tests, we have had to accept ones that cannot distinguish between mild nuisance viruses and their potentially lethal cousin.

With these facts and my personal story in mind, I was troubled to receive an email earlier this month from the multibillion-dollar commercial laboratory Quest Diagnostics with the subject heading, “3 reasons to get an antibody test – NOW.” In an email blast to patients, Quest recommended that individuals consider getting antibody testing to “Give you and your doctor more information to help make your decision about getting back to everyday activity.”

Considering all of the unknowns with the COVID antibody test, it would seem irresponsible for a commercial laboratory to imply a positive test might allow someone to consider a resumption of a normal routine. The message contradicts the Center for Disease Control’s recommendations that those who have a positive antibody test continue to protect themselves and others. Even if someone has definitively had a COVID infection, the likelihood of reinfection is low, but we do not know for certain yet that it is zero.

Adding insult to injury, although Quest says the antibody test will give “you and your doctor more information,” Quest allows patients to order the test for themselves. Shifting the ordering of laboratory tests from providers to patients – and making money in the process – is a slippery slope of transferring health services out of what should be a professional realm into a transparently profit-oriented one. In case you are wondering, the cost of the Quest COVID antibody test is $119 out of pocket.

Opportunism and exploitation are known flaws of our business-oriented, entrepreneurship-friendly economic system. Directly marketing an expensive test of dubious value to consumers, excluding physicians and scientists who might otherwise explain the lack of utility of such a test, and insinuating that the results would permit a return to life as normal are unprofessional claims in a time of needed clarity and scruples.

In the midst of a public health crisis, it is disappointing that the laboratories we depend on as allies for diagnostic answers have executed a mass marketing initiative that is so misguided.

Michelle Finkel is an emergency physician and founder, Insider Medical Admissions. She can be reached on Facebook, YouTube, and on Twitter @Insidermedical.

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