The neutralizing antibodies against SARS-CoV-2 persist in patients for 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. Their presence is essential to fight the infection successfully: those who produce them within the first fifteen days of infection are at a lower risk of developing severe forms of Covid-19.
These are the two main results of a research conducted by the Evolution and Viral Transmission Unit of the IRCCS San Raffaele Hospital, directed by Gabriella Scarlatti, in collaboration with the researchers of the San Raffaele Diabetes Research Institute directed by Lorenzo Piemonti, who developed a particular test for antibodies by exploiting the skills and techniques already used for the study of antibodies involved in the auto-immune response underlying type 1 diabetes.
I study it is published in Nature Communications and offers important indications both for the clinical management of the disease and for the epidemiological containment of the pandemic.
162 positive patients were followed over time to SARS-CoV-2, with symptoms of varying severity, which 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 patient group is made up of 67% males, with an average age of 63 years. 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.
In addition to 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 they are not effective in neutralizing it,” explains Gabriella Scarlatti. “The fear was that their expansion could slow the production of neutralizing antibodies specific to SARS-CoV-2, with negative effects on the course of the infection.”
The early presence of neutralizing antibodies against SARS-CoV-2 has a direct relationship with better control of the virus and increased patient survival. This is true in most cases: 79% of enrolled patients successfully produced these antibodies within the first two weeks of 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, although 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 has no influence in delaying the production of antibodies specific for SARS-CoV-2 and is not associated with an increased risk of serious courses. of Covid-19.
“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” continues Gabriella Scarlatti. “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 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 especially against the new circulating variants, which we are already studying in collaboration with ISS colleagues “.