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Those recovered from Covid are beginning to be a considerable number (almost 230,000 since the beginning of the epidemic). They are also joined by those who with the serological test discovered that they had come into contact with Sars-CoV-2 (due to asymptomatic or symptomatic) after the test reported positivity to IgG immunoglobin, our body’s memory antibodies against infection. But all these people if for various reasons they will come into contact with a positive for the new coronavirus Will they have to undergo fiduciary isolation and possibly a buffer?
The healed
The fact of having been infected and having had the double negative swab indicating recovery four months ago does not exclude that the subject may have a new infection today, test positive on the swab and still be able to transmit the virus immediately. Sure Pierangelo Clerici, President of the Italian Association of Clinical Microbiologists and of the Italian Federation of Scientific Laboratory Societies. Thus even for those recovered from Covid, it is okay to face quarantine (again). In addition, those who become ill and have not undergone a serological test will not be able to know the possible presence of neutralizing or protective antibodies.
Immunity and reinfection
Then there are those who, subjected to serological tests, discovered that they have IgG antibodies in the body. In theory, these subjects could feel immune, but in reality there are still many uncertainties about the actual activity of these antibodies.. At the moment In fact, there is no certainty that positive serological tests are indicative of protective immunity against the virus.. And above all we do not know its permanence in the body. The whole scientific world is studying what antibodies are and their level necessary to protect themselves from reinfection. We don’t know if the antibodies are really protective or how long they last. Until then, everyone will have to adapt to the protocol that provides for isolation if they come into contact with positive people. simplifies Clerici. Although documented cases of reinfection can be counted with the fingers of one hand (with the limit that no antibody tests have been performed, so it is not known if the subjects had developed antibodies), to date the possibility exists of re-disease or simply test positive on the swab and, consequently, be contagious. The fact that you developed antibodies two months ago is not sure if you kept them today.. For all these reasons, even those who have been sick with Covid and those who tested positive for IgG immunoglobes should take the same precautions as the rest of the population: wear a mask, wash their hands frequently, maintain social distancing.
To study immunity, large-scale studies are needed.
For now, studies on the duration of antibodies have given mixed responses.
. In some cases they seem to disappear after three months of infection, in others they last longer. To know how long immunity lasts and to make a correct statistical evaluation we have to wait population studies with important numbers – Clerici clarifies – and I mean about 50-100 thousand people who have been ill and who every week or at most two undergo serological tests to check if they retain the antibodies. These are studies that normally last at least five years because time plays a fundamental role. However, I think that by the end of the year we will start to have clearer answers thanks to the many independent studies launched around the world that all together will be able to give important figures.
The duration of immunological memory.
Finally, let’s not forget that the changes in the immune response from one person to another as seen in the studies carried out so far. And this applies to all infectious diseases. In all vaccines there is also a percentage of 3-5% of the so-called non-responders: people who, despite vaccination, develop few or even no antibodies and immunity tends to disappear quickly. The important concept is that Immunological memory must be developed, the one that really saves us – Clerici concludes -. Anyone who gets sick or is vaccinated against a disease will no longer get sick thanks to the antibodies produced by the stimulation of immune memory. The subject can be reinfected, but does not become ill because T lymphocytes, carriers of immunological memory, stimulate the production of antibodies that block the virus. At Covid we still have to find out if this immune memory is present and in what quantity, how long it lasts and how effective it can be.
October 7, 2020 (change October 7, 2020 | 13:11)
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