Why do children get sick less? Is coronavirus immunity formed? The chief infectious diseases specialist of the Ministry of Health Elena Malinnikova answered the questions that most concern readers.
Julia Borta, “AIF”: Is it true that coronavirus is the most dangerous today?
Elena Malinnikova: Coronaviruses have been known since 1965. In total, about 40 options are currently circulating. Not only in the human population, but also among animals. If we talk about a person, then since the beginning of the 21st century, 4 major viruses of this group have been causing infections. The new one was more pathogenic than the rest. Because the viruses that were observed at the end of the 20th century, although they caused SARS, were not actively transmitted from person to person. And the viruses that we know as SARS (severe acute respiratory syndrome or “SARS” – Red.) that caused the outbreak in 2002, or the coronavirus MERS (middle eastern respiratory syndrome – Red.), which caused the epidemic in 2015 in South Korea, caused SARS and severe pneumonia, but not on such a scale. Today we see activity on the part of the virus and the human community against the virus, so it is believed that this virus is worse and harder. Practice shows that, indeed, the virus has become more contagious than others. But at the same time, the course of this infection can be difficult for not all, but only for a certain contingent of patients.
– How stable is the new coronavirus in the environment?
– The resistance of the virus is evaluated. When transmitted from person to person, any virus can become active or fade away. In principle, in its structure, the new coronavirus is not very stable; it is preserved in the environment under conditions from 7 to 7.5 PH. If the medium is slightly acidic or slightly alkaline, it will not be preserved. Plus, the virus is perfectly destroyed by disinfectants. After 10 minutes, ultraviolet radiation kills him. But there remains a rather serious problem that the virus can well persist on surfaces if, say, it is paper, cardboard, plastic. How long does it last? According to various sources, up to 7-9 or 12 hours. But this is only at a certain temperature and humidity.
– Are children exactly less sick?
– The viruses that cause SARS have a certain specificity. Once in the human body, they can not just hit some cells. Coronaviruses, like influenza viruses, exclusively affect epithelial cells of the upper respiratory tract, lungs, intestines, which have special receptors for them. And the virus acquired this property when it appeared in the human population, breaking the interspecific barrier.
Now it’s hard to say how many animals the virus has passed to humans. But to overcome the interspecific barrier to the virus is very difficult. It is a long process – to find the cell where it can attach to a person. Most likely, this infection began to circulate in China not in December 2019. And the virus appeared a little earlier. And only in December, Chinese colleagues announced the first 41 patients. And from January 13, he began to circulate outside the territory of the PRC.
So, overcoming the interspecific barrier, the virus is looking for cells that it can sit on and continue to use – this is an intracellular parasite – with all the capabilities of the cell. And in the end, it “sits” on cells that have certain receptor proteins. The virus S-protein (forms the very crown) adheres as a hook and adheres to this receptor protein. This allows the virus to penetrate further into the cell. There are not many cells with receptors that are ready to accept the virus in the upper respiratory tract. But the lower the more. There is an assumption that in children these cells with such receptors in the upper respiratory tract are practically absent. That is, the receptors on these cells are immature. They are not ready to accept the virus. Therefore, children can not actively become infected and get sick with this infection.
However, new data on the capabilities of the virus are constantly appearing. At first it was believed that the virus is transmitted only from one person to another, and from him further, to the third, fourth and fifth, no. Now it is also being checked. It is important to understand: when a virus finds its population, where it will circulate, virulence, that is, toxicity, its infectivity decreases. So the new coronavirus just occupied its niche among other viruses circulating in the human population. In general, more than 200 viruses cause SARS.
– How effective is quarantine? Some say it is useless.
– Our task is to prevent serious and fatal outcomes from infection. For this, it is necessary that people at risk who give such severe reactions do not have close contact with people who are able to suffer an infection on their legs or not get sick at all. The quarantine task is isolation. This is by far the best preventative measure. If we do not spread the infection in the population, the incidence will not go along a critical line, but will smoothly cover a certain contingent of the population, smoothly immunize the population. Yes, then we will meet with this infection. But will the virus be as active as its brother SARS or as MERS, which we periodically diagnose, but a little? And how active will he remain for next season? So far the questions remain.
We never get infected with a single virus. We become infected with a cloud of various viruses. How they behave depends on the body. It depends on how much virus has entered the body. Elderly people with cardiovascular diseases and respiratory are most at risk.
– Is immunity to coronavirus formed?
– This is called population epidemiological. When the first recovered appeared, they began to say that immunity after the infection was unstable. Now we are observing the circulation of two variants of the virus – the S-variant and the L-variant. Perhaps they do not give cross-immunity. When the epidemic ends, the virus passes through the human population, we can say how much it forms the immune response, as well as clarify the mortality rate. Now mortality is on average 3.9%, and among the elderly it reaches 20%.
In China, the epidemic lasted about a hundred days. But this forecast cannot be extended to other countries. In general, we cannot say how quickly the infection spreads. Those unprecedented preventive measures that were applied in the PRC did not give an understanding of how the epidemic could develop under normal conditions. And how suddenly the infection began to develop in industrialized countries. We do not see the development of infection in countries where, conditionally, chlorination of water is not practiced. In Soviet times, we had a system of total anti-epidemic control. In Italy, there is no such total control. Plus, many tourist routes flock there. All this played a role in the increase in morbidity. But these are all preliminary conclusions. Many foreign colleagues want us to share our experience on how we deal with this infection.
– Previously, the diagnosis was made after the third test for the virus. Now they say that one is enough.
– Test systems are improving, it is not surprising that new ones are more accurate. Usually when people get sick, they go to the pharmacy (and what would I drink) or open a home medicine cabinet and choose pills to be treated. I urge everyone: as soon as you feel any signs of SARS – sore throat, weakness, malaise, runny nose, especially a dry cough – go home with a mask on and call a doctor. No need to go to the clinic to do tests (“What if they will accept me?”) Or to the pharmacy to look for medicines. Do not go sick to work. Even if you really need it. Such heroism is a crime today. Anyone who is ill can now be potentially a carrier of coronavirus infection. Although it is not necessary that he will be seriously ill. This can be determined by the doctor.