Among the cases of COVID-19 infection, a paradox occurs: there is a complicated form of coronavirus with pneumonia, and the PCR test shows a negative result. This development of events was explained by the systems biologist Ancha Baranova. She says that with coronavirus pneumonia, the virus descends from the upper respiratory tract directly into the lungs. And here the PCR test is already powerless.
There are several reasons for this. First, since its inception, the COVID-19 genome has mutated several times, which allowed it to move around the body more quickly. The second reason may also be the untimely use of the test. That is, much later than the infection occurred. Many people wait several days in self-isolation with the hope that the symptoms will go away on their own. And instead of going to a doctor and getting tested, they drink antibiotics and fill their nose with drops. Such maneuvers will not help get rid of the virus. This only displaces it from the nasopharynx.
For a PCR test, a swab is taken from the nasopharynx. Thus, the professor explains, if the virus has already descended into the lungs, then the test will not be able to detect it there.
Of course, there are alternative ways to detect the virus. In some cases, bronchoalveolar lavage is practiced. However, according to Baranova, this is an extremely unpleasant procedure. During this analysis, the patient is haunted by the feeling that he is choking and he does not have enough air.
Stool analysis is another alternative method for detecting the virus. However, in the absence of the possibility of automating this process and a sufficiently large number of possible viruses, this method is extremely ineffective. Plus, sample analysis is very time consuming.
There are cases in practice when, with prolonged pneumonia, the PCR test is negative. This may be due to the action in the human body of antibodies that our immune system produces.
Baranova suggests that this is possible if the virus is re-infected.
Suppose a person had a mild disease for the first time or had no symptoms at all. At that time, antibodies had already appeared in his body.
After two to three months, upon re-infection, antibodies produced by the immune system begin to eliminate the virus. The fight takes place in places where the greatest accumulation of virus particles is collected. And this is mainly the nasal cavity and nasopharynx. There they are able to supplant or completely neutralize the virus. However, they are not enough for the entire body.
The new antibodies will continue to fight the virus in the lungs. And there, as it turned out, the PCR test cannot detect the virus.
The fight of antibodies against the virus negatively affects the state of the tissues of the internal organs. And this outcome only contributes to prolonged pneumonia. According to Baranova, such an immune response is sufficient for a negative test result. Moreover, this is not enough to completely neutralize the virus. The mechanism of action is complex, so this topic still needs to be understood.
The PCR test is now the most efficient way to detect a virus and is well suited for research. However, he cannot always determine the presence of special antibodies that our immune system produces in the early stages of the disease.