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COVID-19 Testing Update 4-29-20: PCNM Does Antibody Testing

Updated: Jan 4, 2023

Brief Update

Approximately < 1.75% of the US population has been tested.

5.6% of tests were POSITIVE (+)

Total Positive Test Results in the US = 1,030,487



In Oregon, ~ 10,500 tests are processed a week.

2,446 cases as of APRIL 29TH

101 Total Deaths


In March, the FDA began allowing developers to market serological tests as long as they follow guidelines. One reason is for treatment with plasma therapy and another reason is to learn more about the virus and its relationship to us. There is no FDA-approved serological test. To date, Cellex is the only serological test authorized under emergency use (EUA, emergency use authorization). You can find a list of EUA tests here.

When can I expect my test results?

You can expect results for the antibody test in a few days and around a week for NAAT/RT-PCR.

Two kinds of tests are available for COVID-19

1. Test for current infection (NAAT)

2. Test for previous infection (Antibody)


1. From the mouth of the FDA:

"Nucleic acid amplification tests," or "NAAT" tests are molecular tests that detect the virus's genetic material in a sample that typically comes from a patient's respiratory system. FDA-authorized NAAT tests for SARS-CoV-2 meet the EUA statutory standard, and based on the current available data, we believe are highly accurate. This means that a positive or a negative result from a NAAT test is likely to be true. 

The NAAT test is the one we've been using from the get go, the one we had very little of, and the one we test by sticking a swab in your nose, etc. We're looking for the viruses' genetic material. One concern surrounding this tests efficacy is what exactly are we looking for, because the corona-virus is a common virus. It's important that we are looking for genetic material specific to SARS-CoV-2 and not the common cold virus.

If you test NEGATIVE

This doesn't rule out a COVID19 infection. It means that the genetic material was not present in the specimen. Perhaps there wasn't enough virus in the sample. We must consider a false negative. False negative = you tested negative, but you are actually positive. It's important to consider the patient's story (signs and symptoms), when decided what to do next. Retest? It's a bigger problem to have false negative than false positives.

If you test POSITIVE

Genetic material (RNA) was present in the specimen. You are considered "presumptively" infected with COVID19 and contagious. You will be told to quarantine for at least 2 weeks unless you are hospitalized, then depending on symptoms, more quarantine time. Before a diagnosis is made, the doctor will carefully consider clinical observations.

After you're no longer symptomatic, I understand your desire for another NAAT test to see if you are still contagious. Let's say you test negative. The next best test is the antibody test. Read below:


2. Antibody testing

Another type of test, called a serology or antibody test, measures the amount of antibodies present in the blood when the body is responding to a specific infection, like COVID-19. This means the test detects the body's immune response to the infection caused by the virus rather than detecting the virus itself.

Blood collection is necessary for this test.

Picture the COVID19 virus: It's come into contact with a person's lungs. The person's immune system kicks into gear in attempt to destroy the foreign invader. Among many other immune reactions, the body creates antibodies, specifically IgA and IgM at this time. Picture antibodies in the shape of the letter "Y," a bunch of them going towards the virus attaching to it. The antibodies are trying to neutralize the virus and stop it from entering cells. Over time (~4 weeks) our body will produce a different type of antibody, IgG. IgG antibodies are a bit more specific to the invader than IgA and IgM.

(This is a simplified version. Please bear with me.)

The serology/antibody test looks for the presence of these antibodies. Some tests look for only IgG, some for both IgG and IgM, and some for all three!

Want to know another important variable?

It's important to know what ANTIGEN is being used with the antibody test. An antigen is a part of the virus that the antibody attaches to. We want the antigen to be very specific to this particular virus, SARS-CoV-2. If it's not, then we could be testing for antibodies to another coronavirus, the common cold!

If you test NEGATIVE

If you test negative for the antibody test, this could mean a few things. First of all, we must consider false negatives! This means you've been infected or are infectious, but the test comes out negative.

This can happen for a few reasons:

  1. You haven't made antibodies yet. (We don't know the timeline for IgG... when a person makes them, how long they stick around.)

  2. You're immune system is unable to make antibodies because it's compromised.

  3. The test is no good - maybe the test is using the wrong antigens.

If you test POSITIVE

If you test positive for the antibody test, there are antibodies present. We must consider a false positive. A false positive means you actually don't have antibodies to SARS-COV-2, yet you tested positive. We'll never know the truth. A positive result means you may be actively infected with COVID19 or you've cleared it. A positive IgM will lead us to think you may be actively "shedding the virus" and are contagious. A positive IgG will lead us to think you've been infected, but we're unsure if you're contagious.

Since we don't know much about this virus, we can't say whether or not someone is "immune" based off of antibodies. We also don't know if someone with antibodies could be reinfected. Only time will tell.


Let's Chat Vaccines

To put this antibody thing in perspective for you, let's chat briefly about vaccines. A vaccine introduces an antigen to your body, an antigen that is specific to whatever you're attempting to be immune from, like measles, for example. Then, your body makes antibodies (IgM, IgG) specific to this antigen. Now your body has an army ready to fight the measles when you really get infected. Some infectious diseases require a booster shot. This means the IgG your body made the first time is now gone or at a low level, like tetanus. Every so often you need a booster to up those antibody levels, so you're prepared to fight the battle.

Developing a coronavirus vaccine in general has proven to be very difficult. Because the respiratory tract is the main site of infection, this produces more challenges with vaccine manufacture, efficacy and safety. Part of making a vaccine includes ingredients to stimulate a strong enough immune response for the system to produce antibodies.

“If the immune system turns on too strong it can cause damage to the lungs."

“The wrong vaccine could make things worse so we have to be very selective about what part of the virus we want to attack.

Professor Ian Frazer, Immunologist, Queensland University

When it comes to SARS-CoV-2, we don't know how long those antibodies stick around and whether or not they will make us immune to future infections. Remember, like the flu, it's possible this virus could mutate each year. Commence the vaccine guessing game!

Contact PCNM at 503-894-8977 for more information.


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