What do we know at this time about testing for COVID-19 if you are sick
The way to test for the presence of the virus is typically a nasal swab.
The recently available nasal swab tests are very highly accurate if you are ill (meaning fevers plus the other symptoms).
If you are well or suspect you may have been exposed or previously infected , this test will most likely prove negative and not tell us anything we don’t already know. That is that you do not have the virus in your nasal passage.
If you get a home kit for testing when you are ill, be sure to use the nasal swab portion of the test. Do not swab your tongue and throat only as those areas are less likely to be positive.
What we currently know and don’t know about the available antibody tests
These tests look for evidence that your body has experienced the presence of the SARS-CoV2 virus that causes COVID-19. It is that simple. Yes or no is the only answer. You have antibodies or you don’t.
These tests become highly positive two or more weeks after you have become ill.
What these tests cannot tell us:
- whether you are immune from getting a subsequent infection and
- how much antibody you have against SARS-CoV2.
The amount of antibody is important to know. For example, if you had 10 viral particles in your nose, your body would make enough antibody for those 10 viral particles. However that amount of antibody may not keep you from getting ill if someone coughs in your face and you suddenly have a million viral particles in your nose and mouth.
What we can tell you if the test is:
POSITIVE, then you have antibodies to the virus. Will it protect you from later infections? We don’t know, because, as mentioned earlier, we don’t know how much antibody you have. And frankly we don’t as yet know how much antibody you have to have to be protected. We also don’t know how long immunity lasts after getting an infection from this virus. All predictions at this time are just pretty good guesses.
The current tests only tell us yes or no whether you have antibodies. Other testing is in development to be able to tell how much antibody you have if you test positive. Most likely, as testing develops, the current antibody test will develop into a reflex test. A reflex test is one that if you are positive on test 1 (the current antibody test), then you will get test 2. In this case test 2 will determine how much antibody you have. That is for down the road.
NEGATIVE, then with a very high degree of likelihood, you have not been exposed to the virus, even in small amount.
Dr. Gipson
