The number of cases of COVID-19 is on the rise again. Is there a risk of getting infected again for those who have already been ill? Is there an innate immunity? Therapist Alexander Lavrischev answered the most common questions.
How is immunity to coronavirus formed? Can I get sick a second time?
– After an infection or vaccination, our immune system recognizes the pathogen easier and faster, preventing us from getting sick again. The problem is that we still don’t know much about how long-term immunity to coronavirus works. It is assumed that relatively stable immunity (1–2 years) is formed in those who have had an overt disease (that is, not in a latent or asymptomatic form) or have been vaccinated with a drug that has proven its effectiveness in clinical trials. But the infection is new, scientists still know little about how immunity is formed, how well and how long it serves. It takes three to five years to draw evidence-based conclusions.
In this way, now science has not proven a single fact of re-infectionhowever, this does not mean that this will not happen in the future. Since the coronavirus is one of the types of pathogens that can mutate and change appearance, our immune system may need to re-learn to recognize a new type of virus every season – as, for example, happens with the flu.
There is a possibility that in the future it will be necessary to get vaccinated against the coronavirus every year or two in order to “refresh” the memory of our immune systems.
Why does the PCR test show a positive result after recovery? Does this mean that a person is contagious?
– It is assumed that this is not due to re-infection, but to the fact that in some people the particles of the virus are stored in the body more than usual and these people are not able to infect others. On the other side, the accuracy of the PCR test for coronavirus is not absolute, false negative results are possible, that is, when the test shows the presence of a virus, but in fact it is not.
Do not forget that a laboratory sample can be contaminated due to poor preparation of equipment for research. The cells of the mucous membrane of the respiratory tract can live for several months, so they really contain the materials of the virus, but, as mentioned above, this does not mean that a person is infectious, since in none of these cases scientists have not been able to grow a viable virus from the secreted respiratory tract …
Chinese researchers also show evidence that footprints the virus can be detected even 5 weeks after recovery.
According to the Central Research Institute of Epidemiology of Rospotrebnadzor, women are infected with COVID-19 more often than men. The difference is 2-3%.
How long does immunity to COVID-19 last and why does it disappear?
– It is not known for certain how long the immunity to coronavirus remains sufficient to protect you from re-infection. In theory, in individuals with a distinct course of infection, if we draw analogies with the influenza virus, immunity should be guaranteed to work well for a year or two after the illness… And also, in theory, with a re-infection after this time, the immune system should work faster and more efficiently, so that the re-infection will proceed much easier and faster. But that’s in theory. In 3-5 years, enough scientific data will be accumulated to give a more complete answer to this question. Immunity after vaccination is now being actively studied all over the world: while scientists can promise immunity for 1-2 years after one vaccination, however, technologies are being mastered in which one vaccine can give lifelong immunity.
Is it true that some people have innate immunity?
– From the point of view of science, this fact remains unproven. Although there are two small studies, involving about seven newborns, which show that class G antibodies to coronavirus (those responsible for long-term memory of immunity) can be passed from an infected mother during pregnancy to her baby. This immunity will also last for life.
What is herd immunity and how does it protect against infection?
– This term is used in medicine when it comes to the ability of a group of people to resist infection by a pathogen through the personal immunity of each member of the group. The idea is that the incidence drops when enough people around you have either already had the disease (and cannot be reinfected in the foreseeable future) or are vaccinated. Collective immunity, for example, explains the successes and failures of vaccine opponents: in fact, the risk of contracting, say, measles for an unvaccinated person in a group of 99 vaccinated is extremely low, but this does not mean that everyone can do it: a few years ago in one of the Disneylands In the United States, there was a massive infection with measles, as it turned out, due to the fact that, by coincidence, more than half of the people who were supporters of anti-vaccination sentiments gathered in one place. It’s the same with coronavirus or flu: when enough people are vaccinated or ill, the pandemic will subside.
Is the information reliable that those who have had ARVI are less likely to get COVID-19?
– No. Despite the fact that SARS is a collective name for a disease that can be caused by about two hundred types of different viruses, including seasonal coronavirus (the current pandemic is caused by a special member of the group called SARS-CoV-2 (COVID-19), if you have had ARVI, even if it was some other coronavirus, cross-immunity is not formed.
Muscovites can take a test for immunity to coronavirus “Blood (COVID-19 antibodies)” free of charge. Anyone over 18 years of age can take the test. To do this, you need to sign up for the procedure in advance, have a passport and a Moscow compulsory medical insurance policy with you. Blood sampling points are organized in all administrative districts of Moscow. They work every day from 08:00 to 20:00. You need to sign up for the test in advance and arrive at the appointed time.