If the new type of coronavirus stays with us forever, and revaccination becomes an annual routine, then how will our body cope with a second disease? Will it pass more easily or, on the contrary, in a more severe form? There is no definite answer to this question, but the data already available to date indicate that re-infection is no easier than the first.
How often do people get sick again?
Rospotrebnadzor said that repeated cases of infection with a new type of coronavirus do not exceed 1% of all cases. But in these statistics, there are only official cases. Previously, scientists calculated that up to 19.5% of people can become infected with a new type of coronavirus.
For the first time, doctors recorded a re-infection in 2020: a man from Nevada fell ill twice. At first in a mild form, and the second time in a severe one. Even artificial ventilation of the lungs was required. And this is provided that the patient was only 25 years old and in good physical shape.
At first, doctors thought that this was a complication against the background of the first infection, but genetic analysis of samples of the first and second viruses showed that their RNA was different, to be the result of one 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 became infected again if 90 days after a negative test he received a positive one, but there are many nuances.
It is technically difficult to detect repeated cases of coronavirus in humans. 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.
Based on the results of conventional PCR, it is impossible to say whether a 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 research group investigated the median time to relapse in 13 volunteers: it 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, then they would not have known that a person had become infected again. There were also recorded 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 recurrence is more serious than the first. The authors calculated that the average time of the first illness was 16.2 days, and the second was already 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 with COVID-19, only five people from the group were guaranteed to be hospitalized due to the coronavirus. Despite this, even five out of 62 hospitalized are above the usual statistics.
Also, with a recurrence of the disease, there is a high probability of dying: this conclusion was made by the authors of another study, in which two people died for 62 re-illnesses. 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 had a mild or asymptomatic illness once did not receive enough antibodies, because of this, the second infection can be difficult to pass.
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 must be treated with caution: so far, it is impossible to draw unambiguous conclusions about the severity of a recurrent COVID-19 disease.