Antibodies resistant to Covid-19 remain in the blood for at least eight months after infection, according to an Italian study published on Tuesday, May 11. The study, carried out by the San Raffaele Hospital in Milan in collaboration with the Higher Institute of Health (ISS), specifies that this observation is valid “Regardless of the severity of the disease, the age of the patients or the presence of other pathologies”.
“The presence of antibodies, although it decreases over time, is very persistent: eight months after the diagnosis, only three patients” of the 162 follow-ups (29 of whom died) were no longer positive in the test for these antibodies, explain the San Raffaele and the ISS in a press release.
In addition, the early presence of these antibodies is “Fundamental to successfully fighting infection: those who fail to produce them in the first two weeks after contagion are more likely to develop severe forms of Covid-19”.
A new method of antibody assessment
For this study, the researchers relied on techniques already used in the study of the antibodies involved in the autoimmune response underlying diabetes, as well as in the study of anti-HIV vaccines. This allowed them to develop specific tests and a new method for evaluating antibodies neutralizing SARS-CoV-2.
The study, published this Tuesday in “Nature Communications”, made it possible to “Map almost exhaustively the evolution over time of the antibody response to Covid-19”, estimate the ISS and the San Raffaele.
The study was carried out by following 162 SARS-CoV-2 positive patients (67% male, mean age: 63) who presented to the emergency room at San Raffaele during the first wave of the pandemic in Italy. The first blood samples were collected at the time of diagnosis in March-April 2020, the last ones at the end of November 2020. 57% suffered from a pathology other than Covid at the time of diagnosis, in particular hypertension (44%) and diabetes (24%).