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At-Home SARS-CoV-2 and COVID-19 Testing

At-home COVID-19 testing kits are starting to hit store shelves and online shopping sites. With the expected onslaught of tests and testing, what do you need to know to sort through the options? We’ll give you a quick checklist to figure out the best test for you and your family.

These at-home tests are not actually testing for COVID-19; they are tests for the SARS-CoV-2 virus that can identify active infection with this novel coronavirus. COVID-19 is the disease that may result from SARS-CoV-2 infection in some individuals, especially those at increased risk because of age, existing disease, body condition score and weight, and lifestyle. While we are using will use the generic term “COVID-19” throughout this piece, please remember what it actually means.

#1. Emergency Use Authorization

Make sure the test is approved by the U.S. Food and Drug Administration (FDA) under the Emergency Use Authorization (EUA). In short, the EUA allows the FDA Commissioner to authorize unapproved medical products or unapproved uses of approved medical products to be used in an emergency to diagnose, treat, or prevent serious or life-threatening diseases or conditions.

We hope that some of the coronavirus testing will eventually become approved to minimize the number of less accurate tests. For now, all of us must rely on the EUA list.

The EUA list can be found here. A few items of note – you must scroll down the page to find the list. We also discovered that finding some of the EUA tests is difficult since the brand name might differ from the laboratory name, or the product name is not listed. The situation necessitates investigation and patience. You can also write to the company asking for the link on the FDA’s website showing the test’s official status.

#2. Insurance

U.S. federal law now requires private insurers, Medicare and Medicaid to cover COVID-19 tests without any cost to the patient and provides funding to support free testing for some people without health insurance, though it does not guarantee access to no-cost tests for the uninsured.

Sounds simple, right? No – Caveats and nuances abound.

According to the Peterson-KFF (Kaiser Family Foundation) Health System Tracker:

“Importantly, there are limits to federal law coverage requirements that mean some patients with health coverage may nonetheless receive bills for COVID-19 diagnostic testing and related services, and those bills often can be widely different from patient to patient.”

In general, COVID-19 testing needs to be preapproved by a medical professional or physician for your insurance provider or government funding to cover the cost. Some of the at-home test kits are only available with this option.

With other tests, you don’t have to go to your doctor or even have a telehealth visit. You simply fill out a questionnaire. A medical professional will then review your record and will either grant or deny your request.

Other at-home test kits provide a receipt that can be submitted to your health insurance provider for reimbursement.

Why would I get tested if my insurance won’t cover it? Some airlines are partnering with the at-home testing providers that have fast turnaround times. This allows you to skip the 14-day quarantine period necessary for international travel if you complete a test within 72 hours of the last leg of your trip before arriving at your destination.

The best thing to do is to contact your insurance provider once you’ve narrowed down to the right options for you.

#3. Result Turnaround Time

Speaking of turnaround time, this is critical.

Over the summer, you were probably hearing about how turnaround time for some test results were taking anywhere from one week up to two weeks. This doesn’t do anybody any good if the person tested is not quarantining during that period – particularly given the rapidity that this coronavirus can spread.

The laboratories currently offering the at-home COVID-19 testing kits will typically take between 24-72 hours upon receipt of your sample to notify you of your results.

The technology is evolving so quickly that eventually at-home devices likely will be able to give you your results without having to mail in your sample.

#4. Types of Tests: Diagnostic and Antibody

Currently, two different diagnostic tests exist that will show if you have an active SARS-CoV-2 coronavirus infection that can cause COVID-19. The tests do not diagnose COVID-19, but the presence of the live virus in your body.

Diagnostic

Molecular – Detects the virus’ RNA (genetic material). These include various nucleic acid amplification tests (NAAT), reverse polymerase chain reaction (RT-PCR), and loop-mediated isothermal amplification (LAMP). RT-PCR is the most well-known and most widely used at this point.

Antigen – Detects specific proteins (antigens) on the surface of the virus.

Antibody

An antibody test measures your body’s immune response to the virus. It is not recommended for an active SARS-CoV-2 infection and there are no at-home COVID-19 test kits for antibody testing at this time. But, it’s a good thing to know about.

There are five different antibodies: immunoglobulin A (IgA), IgD, IgE, IgG and IgM. For viruses, scientists typically look at IgM and IgG.

Initially, when the body’s immune system mounts a defense against an antigen like a virus, IgM is the first antibody activated and responds within 7-9 days. IgM antibody indicates an active or very recent infection. If someone is tested for an IgM antibody response to a virus, a negative result does not mean one is not infected with a virus. It simply means the body has not yet developed the first line of response to a virus.

Shortly thereafter, IgG production takes over to fight the battle. Typically, it takes about four weeks after the initial response for the IgG antibody response to reach a significant level. When IgG antibodies are measurable, the indication is that the body has either recovered from a viral infection or at least has mounted immunity against that viral strain for a certain amount of time.

Due to this time delay, this is why antibody tests should not be used to diagnose an active coronavirus infection.

Antibody tests are still valuable for your health and for the public health in general. They help us understand people who may be asymptomatic, people who only develop mild symptoms, and people who develop more severe COVID-19.

#5. Sensitivity, Specificity, Accuracy

Sensitivity, specificity and accuracy help us understand how many true positives (TP), true negatives (TN), false positives (FP), and false negatives (FN) are associated with a specific test. They are expressed in percentiles.

Sensitivity – Percentage of true positives that are correct. For example, a test with 90% sensitivity will correctly return a positive result for 90% of people who have a virus or medical condition, but will return a false negative for 10% of the people who have the disease and should have tested positive. Mathematically, this is the equation: TP/TP+FN.

Specificity – Percentage of true negatives that are correct. A test with 90% specificity will correctly give a negative result for 90% of people who truly don’t have a condition. It is calculated as: TN/TN+FP.

Now, we have been avoiding the word “accuracy”. If you were to say to Dr. Dodds, “The accuracy of the test was 95%.” She would respond, “Are you referring to the sensitivity or the specificity?”

The accuracy is, well, less accurate or more general than sensitivity and specificity. Mathematically, it is expressed as: TP+TN/TP+TN+FP+FN.

So when you are selecting a test, look for the sensitivity and specificity.

By the way, the antigen tests available are less specific and sensitive compared to the molecular tests are at detecting an active SARS-CoV-2 infection.

#6. Sample Collection: Nasopharyngeal, Saliva and Blood

The current antibody testing for the novel coronavirus uses serum based via a blood draw or finger prick.

From what we found, the currently available at-home testing kits identify active SARS-CoV-2 molecularly by using the RT-PCR testing method with either a nasal swab or saliva sample.

The laboratories give instructions as to how far up your nose you will have to use a nasal swab.

After weighing the first five points above, you will want to consider what test is most comfortable for you, or even if you should be tested, as these tests are not recommended for general screening of healthy people.

#7. Do Not Use on Companion Pets

Animals exposed to SARS-CoV-2 have displayed only mild transient symptoms and there is no evidence of transmission of the virus from a companion animal to another human.

At this point in time, the Centers for Disease Control and Prevention (CDC), American Veterinary Medical Association (AVMA), and the U.S. Department of Agriculture (USDA) do not recommend routine testing of animals for SARS-CoV-2. In the United States, the decision to test should be made collaboratively between the attending veterinarian and local, state, and/or federal public health and animal health officials.

Specifically, although testing of animals uses the same analytical techniques as those used for humans, the National Veterinary Services Laboratories (NVSL) and other laboratories incorporate animal-specific reagents that also help to preserve needed supplies for testing of humans.

Tying This Altogether

Now that you have a checklist to use in considering whether to obtain an at-home COVID-19 testing kit, let’s apply this in another context to help with your decision.

NutriScan is a food sensitivity and intolerance test for dogs, cats and horses developed by Hemopet.

#1. EUA? Not applicable to this test.

#2. Insurance? Yes; several companion pet insurance policies cover NutriScan. You will need to contact your veterinary health insurance provider.

#3. Turnaround time? Approximately one-two weeks after we receive the sample in our laboratory.

#4. Type of test? An antibody-based test that measures food reactivities with both IgA and IgM antibodies.

#5. Sensitivity and specificity? The sensitivity and specificity of the assay were 95.5% (range 93–99) and 70.7% (range 69–72%), respectively. Antibody IgE serology based testing for food has been found to offer no advantage for diagnosis when performing dietary trials because it had a sensitivity of only 14% and specificity of 87%.

#6. Sample collection? Saliva sample. (So, you can do it at-home.)

#7. Use on humans? No. One veterinary dermatologist performed a double-blinded study at no charge, but then revealed afterwards that the samples included human saliva, street water, and vodka along with saliva from some healthy and suspected food intolerant dogs. These non-saliva samples interfered with the pH of the 47-sample immunoassay plate as well as results for the other clinical client samples on the plate. This is the perfect example of why no one wants you to use the at-home SARS-CoV-2 on companion pets.

References

Baratloo A et al. “Part 1: Simple Definition and Calculation of Accuracy: Sensitivity and Specificity.” Emerg (Tehran). 2015;3(2):48-49, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4614595/.

Commissioner, Office. “Coronavirus Testing Basics.” U.S. Food and Drug Administration, 16 July 2020, https://www.fda.gov/consumers/consumer-updates/coronavirus-testing-basics.

Dodds, WJ. “Diagnosis of canine food sensitivity and intolerance using saliva: report of outcomes.” J Am Holist Vet Med Assoc. 2017/2018;49:32–43, https://hemopet.org/wp-content/uploads/2020/05/DODDS-_1.pdf.

Dodds, WJ. “SARS-CoV-2: Warnings and Testing.” Hemopet, 20 Apr. 2020, https://hemopet.org/sars-cov-2-warnings-testing-april-20-2020/.

SARS-CoV-2 in Animals. American Veterinary Medical Association, 11 June 2020, https://www.avma.org/resources-tools/animal-health-and-welfare/covid-19/sars-cov-2-animals-including-pets.