The Different Types of COVID-19 Tests
Molecular tests detect genetic material – the RNA – of the coronavirus and are sensitive enough to require only a very small amount of it to determine a result. These are the most accurate tests available.
The rapid test used by Seward County (Abbott) is a PCR-based method, which is an RNA test delivering results in minutes. The accuracy is close to 100%. Seward County also uses a Kansas Health and Environmental Lab PCR test. We collect the sample at the Ag Building and send it to their KHEL lab in Topeka, KS. The lab test is even more accurate but requires several days to obtain results, due to the time involved in shipping and processing. Both are PCR tests, which is considered the gold standard for testing.
Southwest Medical Center has its own PCR test and also utilizes the Health Department’s Abbott machines when needed.
Most, if not all, of the other testing sites in Seward County use Antigen or Antibody testing.
Antigen test samples are taken with a nasal or throat swab and detect a protein that is part of the coronavirus. Antigen tests are less expensive and generally faster. The downside is that they can be less accurate. Antigen tests are only able to detect the virus when a patient is at or near peak infection, so one may be infected and contagious for some time before the antigen test is able to detect the virus. A patient may be tested, receive a negative result, and continue to infect others. Depending on the quality of the antigen test and the test takers, false negatives could be as high as 20%.
The CDC has advised people who show COVID-19 symptoms but test negative with a rapid antigen test to get a PCR test to confirm the results. Positive antigen tests are considered much more accurate, but they still can produce false positives.
These are not considered diagnostic tests to determine if someone has an active COVID-19 infection. Antibody tests use blood samples to look for antibodies produced by a person’s immune system to help fight COVID-19. These tests can detect if someone has had a past COVID-19 infection but not if they still are positive for the virus. Antibody testing isn’t recommended until at least 14 days after the start of symptoms, according to the Mayo Clinic. If you test too early—while your immune system is still mounting its defense—it may not provide an accurate result.
Seward County recommends the PCR tests for people that need to know if they are positive.