As the country begins to catch up to the current pandemic, new lab tests are becoming available to check your exposure status to the virus. The different options can be confusing -- let me try to shed some light on them, in a big-picture way.
The Nasal Swab:
This is the first test that became available in this country, and as of today, it is the one that is commonly offered at the free testing sites in our area. It involves inserting a swab approximately 1” deep into the sinuses to take a sample that is evaluated for the presence of viral DNA. In general, the presence of viral DNA signifies an active infection, although there is some evidence to suggest that DNA from dead viral particles left over from a recently-cleared infection could also trigger a positive result on this test. This test is most useful if you are having current symptoms of COVID-19 infection and/or a recent exposure. The test does however carry a high false-negative rate, and up to 30% of actual infections will be missed by the test.
These tests look for the presence of Coronavirus antibodies in your blood. They are not looking for the presence of viral DNA as the nasal swab does, but rather they evaluate your immune system’s response to viral exposure.
Our bodies come into contact with countless microbes every day. One of the primary functions of our immune system is to recognize which pathogens are harmful, then build the appropriate immune “bullets” (antibodies)to kill that particular invader, and later remember what the invader looks like for a quick response next time. A quick response is important, as pathogens multiply into a worse infection during the time that it takes our immune system to figure out how to fight it. In general terms, this is how a prior infection can confer immunity against a future infection: the immune system has now been taught how to rapidly recognize this microbe and has “bullets” ready and waiting to attack it before it gets a chance to multiply.
It is still too early to know exactly to what extent a previous COVID-19 exposure will (or will not) convey immunity to future infections, but given that this is essentially how the immune system is designed to work (and typically does with other viruses), I think it is likely that we will see at least some level of immune protection from the antibodies formed by a prior exposure.
Fortunately, there are now blood tests available to measure the levels of these antibodies, and insurance companies are covering the cost of these tests with no co-pay, when ordered by a doctor.
Serum/antibody tests look at the presence of IgM, IgG, and IgA antibodies. Each antibody is formed at different times and lasts for different amounts of time, so depending on how long it has been since exposure, one antibody may show positive and another may be negative. But a positive result on ANY of them tells us you have been exposed to the virus, and which ones are positive can give us some idea of how long it has been since exposure. Thus, I feel it is most useful to run panels that look for all three of these types of antibodies. Two of my favorites are the panels by Vibrant America and by LabCorp, and both require a blood draw.
Vibrant America does not bill insurance and the cash price of the test is $149, but they have very high rates for accuracy.
LabCorp does take all major insurance plans, so if you have any insurance other than Kaiser or Medicare, your out-of-pocket cost should be $0. For Kaiser patients, you will likely have to have the test ordered by a Kaiser doctor and performed at a Kaiser lab, and for Medicare patients you can go to LabCorp, but will have to have the test ordered by a Medicare doctor to get it covered. Otherwise, you may receive a bill for the full price of the test (which is similar to the cash price for the Vibrant test).
As a service to my patients who may have been exposed to the coronavirus during this pandemic, I am currently ordering COVID-19 antibody screening tests as a free add-on to our regular appointments. If you would like to request stand-alone COVID-19 testing outside of a regular appointment, I am happy to accommodate that as well for a reduced visit fee for both existing and new patients. Since I am not contracted with Kaiser or Medicare, you will not likely get insurance coverage from them for tests ordered by me, but patients with all other insurance plans do seem to be getting full coverage.
If you are interested in setting up an appointment for COVID testing, for a reduced flat fee of $50, we will have a short phone or video visit to discuss your possible exposure timeline and/or symptoms, I will order the appropriate tests, you will go to your local lab for the blood draw, and then when the results come in (usually several days to a week after the test), we will have a second phone, email or video conversation to discuss any questions you may have about the results.
Finally, I should note that many of my patients have expressed concerns about possible exposure by going in to a lab for a blood draw during and after the stay-at-home order. I personally went to LabCorp recently for antibody testing and I am happy to report that I felt much less likely to be exposed there than in other public places such as the grocery store! There was nobody in the waiting room, I was in-and-out in a few minutes, and the staff members were all masked and gloved. In addition, there were signs all over the lab asking patients showing any COVID symptoms to not come in, and announcing that LabCorp does not perform nasal swab testing for acute COVID infection.
If you are interested in setting up a virtual appointment for COVID testing or any other medical concern, please call me at 510-859-8460.
Dr. Rebeccah Shalev, ND