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Why Test Antibodies And What We Have Learned as a Clinic About Our Local Population And COVID 19.

Updated: Jun 3, 2020

In mid-March, we converted our clinic to an urgent care model to test, treat and teach everything COVID. In this process we have learned a tremendous amount about this virus.

1. It is possible this virus has been with us longer than previously thought. We have several patients that have tested positive for IGG antibodies (long term immune response) who swear they were sick with it in December or before.

2. It is true! Many people have no symptoms. We have run many antibody tests and have found that 50% of our patients test positive for the antibodies. This means that many people were just unaware of having the virus at all. Their immune system did what was necessary and beat the virus.

3. 100% of our patients remain out of the hospital.

4. Vitamin C IV’s are helpful. If the IV is used early in the illness it decreases much of the symptomatology of the virus.

5. We have prescribed Plaquenil and Z-Pack for only three patients in the last 2 months. All three patients were very sick with high fevers and chest tightness. On average all three patients had their fevers break and start their recovery in less than 8 hours.

6. Which antibody test you choose really does matter. In our clinic, we are all about choice! Early on we teamed with a private lab called Evexia to give our patients a choice and because at the time any labs run through insurance had no antibody testing to offer. It appears that the insurance-based labs have a small window with which they can measure your antibodies.

7. Below is an explanation of why some Labs Antibody testing will not detect IgG antibodies. Quest and LabCorp use the same method.

Based on the protocol for the Quest serology assay, they appear to call “positive” at a level much higher than DSL’s assay…quite conservative in fact. The DSL (Evexia) assay calls “Detected” at an approximate antibody titer of 1:40 and “Detected-High” at >1:80. Many recovered persons will drop below 1:80 after several weeks, and 1:80 is the minimum titer for plasma donation. Other serology assays don’t call a “positive” until levels are over 1:100. This means that they are likely to only call positive for persons within a very narrow window of about 4-7 weeks from initial infection, maybe a bit longer in some cases. Each person’s immune system is unique in terms of immune response. The bottom line is that there are and will be many serological “false negatives” with other assays due to the fact that they have much higher minimum thresholds and because an individual’s IgG titer will taper off over time…in many cases dropping below the 1:80-1:100 threshold. For this reason, as the pandemic wanes, the sensitivity and low threshold of the DSL assay will prove to be more and more important.

COVID-19 Antibody Testing


· Detects body’s immune response to COVID-19 by measuring specific antibodies associated with COVID-19 (SARS-CoV-2).

· Any positive results should be confirmed using the COVID-19 PCR Test.

· Follow-up testing with the COVID-19 PCR Test should also be considered to rule out infection in individuals with a negative COVID-19 Antibody Test who exhibit symptoms of COVID-19.

· Blood draw required

Please note that negative results do not rule out SARS-CoV-2 infection. Results from the COVID-19 Antibody Test should not be used as the sole basis for diagnosis or exclusion of a SARS-CoV-2 infection. This COVID-19 antibody test is based on a unique fragment of the nucleoprotein from COVID-19 (SARS-Cov-2). Antibodies, IgM and IgG, generated against this fragment have been demonstrated NOT to cross-react with other viruses, including other coronavirus strains. Follow-up testing with the COVID-19 PCR test should be considered to rule out infection in individuals with negative serological results who exhibit symptoms of COVID-19.


IgA –

· IgA antibodies are found in saliva, tears, and blood.

· IgA antibodies protect bodily surfaces that are exposed to outside foreign substances and are found in areas of the body such the nose, breathing passages, digestive tract, ears, and eyes.

· About 10% to 15% of the antibodies present in the body are IgA antibodies.

· A small number of people do not make IgA antibodies.

IgG –

· IgG antibodies are found in all body fluids.

· IgG antibodies are the smallest but most common antibody (75% to 80%).

· IgG antibodies are very important in fighting bacterial and viral infections.

· IgG antibodies are the only type of antibody that can cross the placenta in a pregnant woman to help protect the fetus.

IgM –

· IgM antibodies are found in blood and lymph fluid and are the first type of antibody made in response to an infection.

· IgM antibodies also cause other immune system cells to destroy foreign substances.

· IgM antibodies are the largest antibody and make up about 5% to 10% of all the antibodies in the body.

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