There are direct tests and indirect tests.
- Direct PCR tests are more accurate. Direct tests look for
the virus or portions of the virus itself.
tests are polymerase chain reaction tests (PCR) that react when viral RNA is present. Just like most tests, PCR tests
are very accurate, but the accuracy depends on the amount and quality of the specimens that are tested and the type of RNA
the test examines.
1. There is a viral
test to see if you have the infection right now. This is a PCR (polymerase chain reaction) RNA test that looks for bits of
the virus. In order to get an appropriate sample with a swab that may be placed in the nose, the throat or possibly just in
the mouth. This testing takes several hours after the swab makes it to the special lab that has the equipment to run the sample.
These are the tests that were significantly backed up at some of the large labs. It took several days to get the reports,
but is now down to about 48 hours. The test is to help determine treatment for individuals.
+ A positive tests tells us a person is infected and
should be watched carefully for the possible development of deadly symptoms. While most (over 80%) of us do well and have
symptoms mostly like a cold, some may become extremely ill, with high fever, or shortness of breath or other symptoms that
should lead them to the hospital.
> False positive PCR tests are
extremely rare. There may be false positives if the test is too broad. The current PCR tests are generally tuned very tightly
to the SARS-CoV-2 and are nearly 100% accurate.
- On the other hand a negative
test doesn't mean anything because it tells us only that a person was negative at the moment
in time the test was performed and says nothing about what may happen twenty minutes later when they may be exposed at the
grocery. It is not helpful for any decision-making purpose. If people are confused about the test and think a negative test
is predictive in some way they are mistaken. No medical or workplace decision should ever be based on a report of a negative
> False negatives (A person truly has the virus but their test is negative) may occur if there is too little test
material (generally mucus from the nose or saliva from the mouth) or if the test material is too diluted. Self-testing has
more false negatives because often an individual does not put the swab in deep enough, or leave it in for enough material
to be picked up on the swab. Since false negative corona virus tests may occur, people with continuing symptoms are asked
to follow with their health care provider.
- Indirect tests look for antigens (proteins
produced by the virus) and/or antibodies (immune components made by the human immune system).
These tests have a lower accuracy rate because there may be cross-reacting
(similar) antigens or antibodies from colds or other corona viruses.
These are blood tests, usually have a faster reporting time and have a higher number of false positives and
false negatives or erroneous tests. While the FDA has authorized some of these tests to be marketed, none are actually