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At least 85,000 Bulgarians have contracted COVID-19 since the start of the epidemic in Bulgaria in March, according to data from the coronavirus information portal, which informed those cured of the disease. The actual number of patients is probably many times higher, because not all people with COVID-19 symptoms are tested, because many infected show no symptoms (that is, do not get sick), and because official statistics only report positive, established by PCR tests, but not through the increasingly common rapid antigen tests.
Although there are still many unknowns surrounding SARS-CoV-2 (the virus that causes COVID-19), so far the recovery has given people relative peace of mind that they are generally protected from a new illness. But does that mean they can’t re-infect and transmit the virus to the people they interact with? What scientists have discovered so far shows that infecting a person who is already sick is not impossible, so curing is not 100% safe for others.
Unknown re-infection
The recurrence of COVID-19 has been reported for months, but it has been largely impossible to confirm such data, according to the Massachusetts Institute of Technology (MIT Medical) in the United States. The reason for this is that it is not known whether people had a new positive PCR result due to a second infection or because the test detected residual uninfected genetic material from the first infection.
“Some people have been diagnosed with the virus, it has remained in them for a long time and after reactivation the symptoms of the disease have reappeared. Cases of this type of other viral diseases have been reported to us,” he explained in response to a Dnevnik’s question. “the molecular biologist of the National Center for Associations of Infectious and Parasitic Diseases. Prof. Ivaylo Alexiev.
SARS-CoV-2 is known to change over time from human to human transmission. The process is quite common for viruses and is called a mutation. In this sense, if a person is infected with another variant of the coronavirus and from there draw conclusions about reinfection, it is possible to establish only with a detailed study of the genetic characteristics, the so-called. sequencing. “However, this sequencing must be done for both the first virus and the second. To compare and see that they are different,” said virologist Prof. Radka Argirova, adding that both samples should be stored.
In this sense, the PCR test only shows if the virus is present in the body (assuming that no more than 14 days after the onset of symptoms, the person is no longer infected by others), but not what their genetic characteristics are . “The SARS-CoV-2 strain has so far described 13,000 variants. Therefore, a person can become infected with another variant of the virus. But this must be demonstrated,” explains Professor Argirova, adding that not all variants of the coronavirus survive and they manage to spread.
“It all depends on whether it is a new variant of the coronavirus that has reinfected the person or there are some remnants of the previous one,” said the virologist, adding that it is possible that a person does not have symptoms of reinfection, but
“mechanically transmit the virus to another person who does not have antibodies”
The specialist recalls that not all people who have had the coronavirus have antibodies and therefore their absence or availability must also be accredited in the laboratory.
In Bulgaria it is not known that genetic tests are done to establish a reinfection, but the possible reinfection of four employees of the Military Medical Academy (MMA) was commented weeks ago by the head of the hospital and president of the coronavirus gene. Ventsislav Mutafchiiski. In one of the cases, the man had bilateral bronchopneumonia in June and “reinfection took place in Croatia in the fall, in which the employee’s daughters became infected,” Mutafciiski said, adding that the hospital was unable to perform a genetic test. to confirm reinfection. According to the general, in two of the employees the clinical picture is more severe than in previous months, and in the other two the symptoms are significantly milder.
Infected does not mean sick
Not all people infected with the coronavirus show symptoms (that is, they get sick), but every infected person transmits the infection, such as the first and possibly the next infection. The case of proven recurrent asymptomatic infection, cited by various scientific journals and the media, is that of a 33-year-old man living in Hong Kong.
In March, he tested positive for COVID-19 and had symptoms such as a cough, dry throat, fever, and headache. He made a full recovery, but in mid-August a PCR test again confirmed that he was infected, this time without symptoms. According to professor of immunology Akiko Iwazaki, cited by Time, these cases are encouraging because “although he is infected, it is a good example of how immunity should work in humans.”
“Unfortunately, we still do not know what immunity a person has after recovering from COVID-19, or how long it lasts,” wrote the Massachusetts Institute of Technology Institute of Health. In this context, the scientific journal The Lancet reported in October on a 25-year-old man from the United States, whose reinfection was more severe than the first and the man had to be admitted to a hospital to help him breathe oxygen.
It is more worrying for others
In a mid-November article, the University of Pittsburgh in the United States reported that it was entirely possible for a person to become infected again, even with the same variant of the coronavirus. If the reinfection is the same, it is likely to be less severe due to the body’s immune response, which has produced antibodies against the virus.
“But the risk to you in this case is of secondary importance. It is more worrying that someone is infected with the same option, that they do not get sick, but that others become infected. This is a big public health problem,” he wrote. college publication.
The Institute of Health at the Massachusetts Institute of Technology summarizes that scientists have recently documented four cases of reinfection, unequivocally demonstrating that it is possible.
The latest reports are of two Indian healthcare workers who tested positive for the second time, three and four months after the first infection, respectively. They had no symptoms the first or second time, but the concern is that they both had higher levels of the virus when they were reinfected. This means that, although they are asymptomatic, they were likely to have been more contagious and better able to spread the virus when they were reinfected.
Again: it’s about the vaccine
The issue of immunity after coronavirus infection has been relevant since spring, especially in the context of the effectiveness of developed vaccines. Therefore, scientists, including the Bulgarian health authorities, have repeatedly stressed the importance of vaccines for communities, as they can prevent the (severe) disease of the immunized individual, but this does not mean that if a vaccinated person is infected, You cannot transmit the infection to others who are (no longer) immune or who have not been vaccinated.
A New York Times article reports that Pfizer https://news.google.com/ Pfizer / BioNTech and Moderna have only tracked how many people have been vaccinated in their vaccine trials. people have contracted COVID-19, leaving open the possibility that some of those immunized will become infected without developing symptoms and therefore “transmit the virus silently, especially if they are in close contact with other people without wearing masks.”
According to the virologist Prof. Radka Argirova, after the development of the SARS-CoV-2 vaccine, “there are no more possibilities” because, when transmitted from person to person, the virus has undergone many changes that science has taken into account. “From now on, any variation that the virus inevitably undergoes will not remain stable and will not affect its pathogenicity. (possibility of causing illness – author’s note), neither in its prevalence nor in the impact of vaccines. This is just part of the law of evolutionary virology, “Professor Argirova said in an interview with BNR.
More on the topic of the coronavirus.
