When we test positive to COVID after being vaccinated, we are testing positive to the spike protein, which is produced by the RNA which was picked up by our immune cells with which we were vaccinated or when we were originally infected with the virus.
According to the website medicinenet.com, which has the most succinct and accurate definition of the tests that I have been able to find, the difference in the various forms of testing is the following:
The PCR test looks for the presence of the COVID-19 virus by detecting its genetic material (RNA) through a technique called reverse transcriptase-polymerase chain reaction (RT-PCR). If the sample contains the virus, its RNA will be extracted. The RNA is converted to DNA and made into several copies. These DNA copies are then detected by a machine.
The PCR test is currently the most accurate test for diagnosing COVID-19 virus infection and has a low risk of false-negative results (a false-negative occurs when you get a negative PCR result even though you are infected with the virus).
The antigen test detects bits of certain proteins, called viral antigens, present on the surface of COVID-19 virus. Samples are taken from nasal swabs.
This test is also referred to as a “rapid test” because results may be available much faster (within 15-60 minutes). One advantage of that is that it can allow for more immediate diagnosis and treatment if you test positive, since the antigen test is highly specific for COVID-19.
However, antigen tests have a high rate of false-negative results and are not as accurate as PCR tests. [i]
The FDA website[ii] also has a helpful definition of the two types of testing:
“There are two different types of tests – diagnostic tests and antibody tests. A diagnostic test can show if you have an active coronavirus infection and should take steps to quarantine or isolate yourself from others.
Currently there are two types of diagnostic tests – molecular (RT-PCR) tests that detect the virus's genetic material, and antigen tests that detect specific proteins on the surface of the virus. Samples are typically collected with a nasal or throat swab, or saliva collected by spitting into a tube.
An antibody test looks for antibodies that are made by the immune system in response to a threat, such as a specific virus. Antibodies can help fight infections. Antibodies can take several days or weeks to develop after you have an infection and may stay in your blood for several weeks after recovery.”
When you have been infected with the virus, then indeed you are contagious to other people both before you develop symptoms and for several days after the infection has cleared. Hence the recommendation for 10 to14 day quarantine after exposure.
It is not at all clear to me that testing positive (or negative, for that matter) necessarily means that you are infectious. Some people do appear to shed virus for an undetermined length of time, despite having antibodies in their blood.[iii] Even the revered UpToDate.com has no definite information about how long we are infectious – the literature reports positive viral particles anywhere from two days to several months after active infection.[iv]
So bottom, line when you test positive after receiving a vaccine, you may be testing positive to the spike protein which is produced as part of our antibody response to infection. A positive antibody test simply means prior exposure and immune system response to that exposure, not necessarily active infection.
In the end, this is a disease similar to influenza which I think we are all going to acquire at some point. It is our choice whether to live in fear, or to live with the expectation that our lives will end when they are destined to end.
Smart precautions would be things we all learned in kindergarten:
- wash your hands.
- flush - don’t leave dirty Kleenex lying around.
- don’t go to work if you are very sick.
- cover when you cough or sneeze, as a courtesy to others.
- wear a cloth mask or a face shield to prevent your droplet secretions from landing on your neighbor.
- let us forgive those who have wronged us, and live life to the fullest every day, with because none of us can predict our end.