Scientists from Italy and Sweden have found that antibodies to coronavirus in most of those who have been ill persist for up to 15 months, writes Rossiyskaya Gazeta, citing an article published on the bioRxiv preprint service.
Scientists, based on the analysis of blood samples from 136 patients with coronavirus and analysis of the plasma of 108 people who had a negative PCR test result, measured the titers of anti-S and anti-RBD antibodies.
Thus, in patients recovering from COVID-19, anti-RBD immunoglobulins IgM and IgA were increased by 77% and 85%, respectively. In the next 6-15 months, they decreased to 4.5 and 11%. In the first three months after the disease, IgM and IgA antibodies to the S-protein were fixed at 88 and 90%.
At the same time, the maximum level of IgG antibodies to RBD and S-protein in almost all patients was recorded 15-28 days after the onset of symptoms. They then gradually declined over six months and stabilized for up to 15 months. Those who were seriously ill had high antibody levels for longer.
Scientists also compared the rates of those who received immunity to coronavirus after illness with those who were vaccinated. It turned out that 14-35 days after the first dose of the vaccine, the titers in those who received the vaccine were at the same level as in those who had recovered six months after infection. The second dose of the vaccine brought them to the same level as in recovering patients.
The authors conducted the study within 15 months after the respondents recovered. They believe that this is not enough to assess long-term immunity. At the same time, it is noted that in many of the patients, B- and T-cells of “memory” and neutralizing antibodies were retained in the blood plasma during this period.
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