How often do people get sick again?
Rospotrebnadzor said that repeated cases of infection with a new type
For the first time, doctors recorded re-infection in2020: a man from Nevada got sick twice. First in a mild form, and the second time in a severe form. Even artificial ventilation was required. And this provided that the patient was only 25 years old and was in good physical shape.
At first, doctors thought that this was a complication due to the first infection, but genetic analysis of samples of the first and second viruses showed that their RNA was different and could be the result of the same infection.
Another British study shows that, having been ill with COVID-19 once, a person receives only 83% protection against re-infection.
Is it possible to understand that a person got sick a second time and how
Doctors believe that a person has become infected again if he receives a positive test 90 days after a negative test, but there are many nuances.
Identify repeated cases of coronavirus in humanstechnically difficult. Therefore, most likely we do not see most of those who have been ill twice or more. To determine that a person has become infected again, and not just got complications from the first disease, it is necessary to conduct a complete reading of the genome of the virus isolated in the patient's samples. But this is done extremely rarely.
According to the results of conventional PCR, it is impossible to saywhether the person has previously suffered from COVID-19 or not. The coronavirus can exist inside the body for a long time even after the cough and other external symptoms have ended. A reliable criterion for re-infection is considered to be positive PCR 90 days or more after a negative result. But this does not always work.
Another scientific group studied 13volunteers, the median time of recurrent disease was 60 days. This means that half of them caught the infection before 60 days had passed, and half - after.
If scientists had not sequenced the genome of the virus, thenthey would never have known that the person had become infected again. There have also been cases when the genome of the virus was read and it was almost the same as the previous one. Similar, but not identical.
Therefore, even a complete reading of the genomes of the virus does not at all guarantee that you will identify all re-ill patients.
The second time the disease is easier or more severe
A Brazilian study indicates that recurrent illness is more severe than the first. The authors calculated that the average time of the first illness was 16.2 days, and the second - 19.4 days.
Another work of scientists from the United States confirms that out of 62 re-illnesses, 31 had symptoms of the disease, and 18 were hospitalized within 30 days after the second infection.
True, not all of these hospitalizations were associated withCOVID-19, only five people from the group were guaranteed to be hospitalized due to coronavirus. Despite this, even five hospitalized out of 62 is higher than usual statistics.
Also, with a recurrence of the disease, there is a largeprobability of dying: this conclusion was made by the authors of another study, in which 62 people who had re-illnesses, two died. But the point may also be that the sample is very small.
Why a second illness can be worse than the first
Scientists suggest that a person who has been ill once in a mild or asymptomatic form has not received enough antibodies, which is why a second infection can be difficult.
That is, those who were seriously ill for the first time may have a reduced risk of getting sick again.
Note that all the studies described in the text should be treated with caution: so far it is impossible to draw unambiguous conclusions about the severity of a recurrent COVID-19 disease.
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