Rome, April 14 (beraking latest news Health) – Neutralizing antibodies against Sars-CoV-2 in recovered patients are still active 11 months after infection. This is what emerges from a research carried out by the virology laboratory of the National Institute of Infectious Diseases’ L. Spallanzani ‘in Rome, directed by Maria Rosaria Capobianchi, just published in the magazine’ Viruses’. The antibodies “are still present at consistent levels,” the research adds.
The researchers of the Virology Laboratory analyzed, between February 2020 and January 2021, 763 serum samples from 662 Covid-19 patients, taken during hospitalization at Spallanzani or after passing the infection, during follow-up checks or screening for potential immune plasma donations. “These samples were then subjected to seroneutralization, a classic virological technique – explain the researchers – with which the ability of blood samples to neutralize the live virus is verified, and which represents the ‘gold standard’ for determining the protective efficacy of antibodies, being more precise and reliable than the pseudovirus technique used by many research groups today, especially those who do not have biosecurity laboratories such as those present at the Inmi “.
The research found “first of all that the levels (or titers) of neutralizing antibodies are higher in people over the age of 60, and the higher the more severe the respiratory symptoms manifested by patients – observes the study. higher were achieved by patients who manifested the so-called Ards (Acute Respiratory Distress Syndrome) with a P / F ratio (the ratio between the oxygen pressure in arterial blood and the percentage of oxygen inspired by the patient) of less than 200 mmHg ” .
The most significant aspect of the research, however, was the confirmation that most of the patients followed for at least six months and for a maximum of eleven months “maintained a consistent level of neutralizing antibodies – the research specifies – In about 60% of cases. followed by neutralizing antibodies peaked between one and two months after infection, decreased slightly between two and three months, and subsequently remained stable for up to eleven months after infection. antibodies have shown a trend of continuous descent, without however ever reaching the level of not being detectable. Finally, in about 15% of cases, the neutralizing antibodies showed an opposite trend, increasing over the period observed “.
The data emerging from the research have important practical consequences. The Spallanzani researchers have in fact developed an algorithm for screening convalescent plasma donors, which allowed to reduce the number of samples subjected to neutralization tests, and therefore the workload of the laboratory, without a significant loss of suitable donations. But the data that emerge from the research are important “above all from an epidemiological point of view, because they provide support to the hypothesis that the duration of the protection conferred by natural infection and vaccines can go beyond the eight to ten months hypothesized up to now by the literature. on the subject, “scientists warn.
“Seroneutralization, even if complex and demanding in terms of time required and skills of the operators, remains the reference tool for the evaluation of antibody-mediated immunity after Sars-CoV-2 infection – say Giulia Matusali and Francesca Colavita , two of the authors of the study – Using intelligent testing algorithms we were able to optimize the laboratory workflow to monitor antibody-mediated protection in Covid-19 patients, plasma donors and vaccinated individuals ”.