A new American study, published in the journal Science was used to estimate the duration of immunity when a person contracted Covid-19. According to the results, it would be 8 months.
The immune memory of Sars-Cov-2
Since the emergence of the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), scientists have been studying it. One of the questions most people ask themselves is how long are we immune to when we have had Covid-19? In order to understand the immune memory of the new coronavirus, improve diagnostics and vaccines, and assess the course of the pandemic, researchers in the United States analyzed the virus in 254 samples from 188 infected patients (80 men and 108 women), coming mainly from California or New York. Most of them had a mild or moderate form of the disease and 7% had to be hospitalized, some in intensive care unit. The research focused on different levels of antibodies as well as immune cells, such as B lymphocytes, CD8 T lymphocytes and CD4 T lymphocytes. The results revealed that the effectors (responses to stimulation) of immune memory are still present for up to eight months after the onset of the first symptoms of Covid-19. When a pathogen enters the body through natural contamination or through a vaccine, immune memory is built. Part of the antibodies are directed against this pathogen while the other part works to create memory cells, which will recognize the pathogen in question, the goal being to fight it quickly during a next infection.
Circulating antibodies
Scientists followed the patients by observing the circulating antibodies against Sars-Cov-2. They found that the amount of antibody remained stable between 20 and 240 days after the onset of clinical signs. It turned out that 98% of the participants had anti-protein S (Spike) antibodies in their blood serum after one month. Later, after six months, the amount of these antibodies drops, but remains present for 90% of people. Moreover, concerning neutralizing antibodies, they persist beyond six months for 90% of patients, or even up to eight months. Neutralizing antibodies block the entry of the virus into the body. There is therefore a lasting anti-coronavirus immunity, up to eight months after the appearance of the first symptoms of the disease, even if the quantity of antibodies is not heterogeneous in all individuals.
