Rome, 11 May 2021 – The antibodies neutralizing against the SARS-CoV-2 persist in patients for at least eight months from the diagnosis of positivity. Therefore, there is no variation in the severity of the disease, age and possible presence of other pathologies in Covid patients. This is the main result of an Italian study, conducted bySan Raffaele Hospital in Milan in collaboration with theHigher Institute of Health (Iss). Not only that, the presence within 15 days of infection of antibodies in the immune systems of those affected by the virus is critical to successfully fighting the infection without developing severe forms.
The research team, using techniques already used in the study of the auto-immune response of type 1 diabetes and for vaccines against HIV, has developed a new test for antibodies against Covid. An additional tool in the fight against the virus, the study, published today in Nature Communications, because it allows map the evolution of the antibody response over time to Covid-19 and provides important indications both for the clinical management of the disease.
Satisfaction with the success of the research was expressed by Andrea Cara and Donatella Negri, researchers of the Istituto Superiore di Sanità. “This work represents an exciting collaborative effort” –underline the two coordinators of the ISS research team- “which combines our interest in the evaluation of the immune response against different infectious agents with the experience within our institutions, focused on the development of innovative immunological methods, effective and capable of giving quick responses”.
Let’s see how the study was conducted and the results obtained.
The study method
I’m 162 patients, positive for Covid during the first wave of the pandemic, the subjects of the study in question. The group of infected, with an average age of 63 years and made up of 67% of males, presented themselves to the emergency room of the San Raffaele Hospital in Milan with symptoms of varying severity. More than half, about 57%, in addition to the Coronavirus, suffered from one second pathology, hypertension and diabetes the most frequent. At the time of diagnosis, the collection of the first blood samples began, dating from March-April 2020 to the last at the end of November and 134 patients of the total 162 were then hospitalized.
In addition to specific antibodies against SARS-CoV-2, the researchers also monitored the reactivation of antibodies to seasonal Coronaviruses which are responsible for the classic cold, with the aim of verifying their impact on the response against SARS-CoV-2. “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”, explains Gabriella Scarlatti, who coordinated the research, and adds “These antibodies partially recognize the new Coronavirus and can reactivate following the infection, although they are not effective in neutralizing it“.
The results obtained
Unlike previous studies this research has highlighted the correlation between the early presence of Covid antibodies and increased patient survival, given by better virus control. In fact, 79% of the patients studied produced antibodies within fifteen days of the onset of symptoms. Those who did not succeed, regardless of factors such as age and previous health, instead risked developing severe forms of the virus.
Ma how long the presence of antibodies against Coronavirus lasts in the blood? Except in three cases in the subjects studied, the defenses remained for at least eight months after diagnosis, regardless of age and previous pathologies. This is the first good news: “The immune protection conferred by the infection persists for a long time“Says Gabriella Scarlatti who then focuses on the risks that those who do not develop defenses run in the first days of diagnosis:” What we have discovered has implications both in the clinical management of the disease in the individual patient, and in the containment of the pandemic “says the coordinator of the research team, who explains: “According to our results, in fact, patients unable to produce neutralizing antibodies within the first week of infection should be identified and treated early, as they are at high risk of developing severe forms of the disease “. The second important result is that seasonal Coronaviruses, the classic colds that affect millions of Italians every year, they have no influence in delaying the production of SARS-CoV-2 specific antibodies and therefore their presence is not correlated with a greater risk of severe disease courses. Now the next goal, which the researchers are working on, is to understand effects of new variants and vaccination on immune responses.
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