Scientists have found out why some people quickly recover from COVID-19
Some patients recover quickly even after a fairly acute period of COVID-19 disease. A new study offers an explanation for this phenomenon.
A group of American doctors observed patients who had suffered COVID-19 in mild or moderate form. They managed to draw some interesting conclusions that may reveal one of the mysteries of the coronavirus.
According to the results of the study, some patients not only tolerate the disease more easily, but also get a longer-term immunity to re-infection after it.
The study also sheds light on why this is happening.
What did the scientists find out?
The results of the study were published in the authoritative publication Cell.
Researchers studied blood samples from patients with coronavirus in Boston in the spring and summer of this year. They were interested in antibodies in the blood of patients long after the disease was defeated.
According to Duane Wesemann, associate professor at Harvard Medical School, doctors have discovered that there is a category of patients who quickly recover from coronavirus, and the level of antibodies in their blood after that reaches high levels.
This indicates that the body is preparing to defend itself against future attacks by the same virus, Wesemann explains.
The researchers divided patients into two groups, depending on whether antibodies, including immunoglobulin-G (IgG), remained in the blood for several weeks after the disease.
It turned out that in most patients who had COVID-19, the level of igG in the blood fell to extremely low levels in about 3-4 months. Thus, patients who recovered in May were again virtually defenseless against the virus by September-October.
And only in 20% of patients the level even after four months remained as high as immediately after recovery. Moreover, in some of them, the amount of antibodies to coronavirus even slightly increased over time.
After studying the medical histories of these patients, the researchers found that they had symptoms for about 10 days on average during the illness.
At the same time, the average period of observed symptoms in those 80% of patients whose antibody levels dropped after the disease was 16 days.
Another significant discrepancy was the genetic differences in the structure and number of two types of cells of the immune system ( T and B cells). These cells play an essential role in the functioning of the " immune memory" and the protection of the body from the threats that it has already faced.
According to Wesemann, the data obtained indicate that the immune system in these 20% not only meets the virus more aggressively, but produces cells better, capable of protecting the body in the long term.
The next task will be to find out the reasons why patients included in this 20% have such differences in the structure of the immune system. This can go a long way towards understanding how human immunity generally works.
In the meantime, it is obvious that we are talking about genetic heritage. Some people have an innate defense against viruses like Sars-Cov-2.
The riddle of immunity
A group of British and German scientists conducted a study among residents of Germany, which showed that 35% of people who have not had coronavirus have antibodies in their blood that can fight it.
According to scientists, these cells were "probably acquired in previous infections by endemic" coronaviruses. This feature of immunity is called cross-reactivity.