Covid, how long do antibodies last after infection? According to a research conducted by the Irccs San Raffaele of Milan in collaboration with the Higher Institute of Health, “neutralizing antibodies against Sars-CoV-2 persist in the blood for at least eight months after infection”. According to the study, “neutralizing antibodies persist in patients up to at least eight months after the diagnosis of Covid-19, regardless of the severity of the disease, the age of the patients or the presence of other diseases. Not only – the researchers highlight – the their early presence is essential to successfully fight the infection: those who fail to produce them within the first fifteen days of infection are at greater risk of developing severe forms of Covid-19 “. The study, published in ‘Nature Communications’, “maps in such an exhaustive way the evolution over time of the antibody response to Covid-19 and provides important indications both for the clinical management of the disease – through the recognition of patients at greater risk of serious – both for the epidemiological containment of the pandemic “, explain the experts. The research, conducted by the Evolution and Viral Transmission Unit of the Irccs San Raffaele hospital, directed by Gabriella Scarlatti, in collaboration with researchers from the San Raffaele Diabetes Research Institute directed by Lorenzo Piemonti, has developed a particular test for antibodies by exploiting the skills and techniques already used to study the antibodies involved in the auto-immune response underlying type 1 diabetes. Department of Infectious Diseases of the Higher Institute of Health (Iss), coordinated by Andrea Cara and Donatella Negri , taking advantage of the skills and techniques already used for the study of HIV vaccines, they worked closely with Gabriella Scarlatti’s group to develop a new method for the evaluation of neutralizing antibodies against Sars-CoV-2. was conducted following 162 Sars-CoV-2 positive patients, with symptoms of varying degrees, who presented themselves to the emergency room of the San Raffaele hospital during the first wave of the pandemic in Italy. The first blood samples were collected at the time of diagnosis and date back to March-April 2020, the last at the end of November 2020. “The group of patients is made up of 67% males, with an average age of 63 years – reports the research – 57% suffered from a second disease in addition to Covid-19 at the time of diagnosis, hypertension (44%) and diabetes (24%) the most frequent. Out of 162 patients, 134 were hospitalized “. specific and neutralizing antibodies against Sars-CoV-2, the researchers also investigated the reactivation of antibodies to seasonal coronaviruses (those responsible for the classic cold) in patients with the aim of verifying their impact on the response against Sars-CoV-2 . “These antibodies partially recognize the new coronavirus and can reactivate following the infection, although not effective in neutralizing it – explains Gabriella Scarlatti, who coordinated the research – The fear was that their expansion could slow down the production of neutralizing antibodies specific for SARS -CoV-2, with negative effects on the course of the infection. “” This work represents an exciting collaborative effort – underline Andrea Cara and Donatella Negri – which combines our interest in the evaluation of the immune response against different infectious agents with experience within our institutions, focused on the development of innovative immunological methods, effective and capable of giving quick responses “.” Contrary to what emerged from previous studies, the early presence of neutralizing antibodies against Sars-CoV-2 is actually correlated better control of the virus and increased survival of the PA patients – the researchers recall – Fortunately this is true in most cases: 79% of enrolled patients have in fact successfully produced these antibodies within the first two weeks of the onset of symptoms. Those who did not succeed were at greater risk for severe forms of the disease, regardless of other factors such as age or health. At the same time, the presence of neutralizing antibodies, while reducing over time, was very persistent: eight months after diagnosis there were only three patients who no longer showed positivity to the test. The persistence of these antibodies for at least eight months is independent of the age of the patients or the presence of other pathologies “. Finally, according to the data analyzed by the San Raffaele researchers,” the reactivation of pre-existing antibodies for seasonal coronaviruses did not no influence in delaying the production of specific antibodies for Sars-CoV-2 and is not associated with an increased risk of serious COVID-19 courses “.” The study of the antibody response against Sars-CoV-2 – explains Vito Lampasona of Diabetes Research Institute – reveals the complexity of the interaction between the virus and the immune system, one of the elements that determines the different severity with which the disease manifests itself in the individual patient “.” What we have discovered has implications both in the clinical management of the disease in the individual patient, both in containing the pandemic – says Scarlatti – According to our results, in fact, patients unable to produce neutralizing antibodies within the first week after infection, they should be identified and treated early, as they are at high risk of developing severe forms of the disease. The same results, however, also give us two good news: the first is that the immune protection conferred by the infection persists for a long time; the second is that the presence of a pre-existing antibody memory for seasonal coronaviruses does not constitute an obstacle to the production of antibodies against Sars-CoV-2. The next step is to understand if these effective responses are maintained even with vaccination and above all against the new circulating variants, which we are already studying in collaboration with ISS colleagues “.
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