PROPERTIES OF RBD SPECIFIC IGG FROM COVID-19 PATIENTS AND SPUTNIK V VACCINATED INDIVIDUALS [СВОЙСТВА АНТИТЕЛ К RBD У ПЕРЕБОЛЕВШИХ COVID-19 И ВАКЦИНИРОВАННЫХ ПРЕПАРАТОМ «СПУТНИК V»]

SARS-CoV-2 specific antibody response is a generally accepted measure of postinfection and vaccination-induced immunity assessment. The dynamics of avidity maturation and neutralizing activity of virus-specific immunoglobulins G during the SARS-CoV-2–associated coronavirus infection was studied in cohorts of vaccinated volunteers and COVID-19 patients. 4–6 months after vaccination, neutralization activity was low compared to hospitalized patients (medians 57.4% vs 86.4%). On the opposite, the avidity indices in vaccinated volunteers were significantly higher (median 76.7%) than among hospitalized patients (median 61.4%). During the acute phase of the disease (14–16 days PI), post-vaccination patients have also higher avidity indices than primary patients (medians 43.5% vs 20.4%). Our results suggest that in long-term perspective antibody affinity maturation rate is higher after vaccination than after a natural infection. We demonstrated that Sputnik V vaccination leads to formation of high-avidity IgG, which persists for at least 6 months of observation. These results also indicate the presence of protective efficacy markers for at least 4–6 months after the vaccination or a previous illness and gives grounds for the half-year time period chosen for booster immunization with Sputnik V in Russia. © 2022 Pirogov Russian National Research Medical University. All rights reserved

ASSESSMENT OF COVID-19 CLINICAL COURSE IN PATIENTS VACCINATED WITH SPITNIK V, SARS-COV-2 S PROTEIN RBD DOMAIN VARIATION AND SERUM VIRUS NEUTRALIZING ACTIVITY

The COVID-19-associated mortality remains high. Studying the features of the COVID-19 course in vaccinated patients, who have got ill on different dates after vaccination, compared to unvaccinated individuals is relevant. The study was aimed to assess clinical and immunological features of the COVID-19 course, as well as to assess humoral immunity (virus neutralizing activity, VNA) and SARS-CoV-2 S protein RBD domain variation in the groups of patients, previously vaccinated with Sputnik V, and unvaccinated patients. A total of 251 patients with confirmed diagnosis of COVID-19 were enrolled, of them 116 individuals were previously vaccinated with one or two Sputnik V vaccine components, and 135 patients were not vaccinated (comparison group). Individuals over 50 years of age prevailed (82.8%). The patients, who received two vaccine components, had mild to moderate COVID-19 (92.1%). In the group of unvaccinated patients, 11 individuals received treatment in the ICU, 10 of them died. The viral load was significantly lower in vaccinated patients. Mutations of SARS-CoV-2, such as S477N, S477N+A522S, E484K and E484K+S494P, were identified both in vaccinated and unvaccinated patients. Assessment of the neutralizing activity of sera revealed no significant differences in VNA against different variants of SARS-CoV-2 mutations. The data obtained demonstrate that the lack of vaccination is an aggravating factor and is capable of increasing the risk of severe course and death in patients with COVID-19