RESUMEN
The level and duration of protective immunity are often analyzed qualitatively or semi-quantitatively. The same strategy is applied to the analysis of antibody dynamics. At some point in time t after exposure or immunization, the presence of immunity against the infection is inferred from the level of specific antibodies by comparing it to a reference value. This approach does not account for the stochastic nature of human disease after exposure to a pathogen. At the same time, it is not fully clear what antibody level should be considered protective. The aim of this study was to develop a mathematical model for quantitative determination of protective immunity against SARS-CoV-2 and its duration. We demonstrate that the problem of describing protective immunity in quantitative terms can be broken down into 2 interrelated problems: describing the quantitative characteristics of a pathogen's virulence (in our case, the pathogen is SARS-CoV-2) and describing the dynamics of antibody titers in a biological organism. Below, we provide solutions for these problems and identify parameters of the model which describes such dynamics. Using the proposed model, we offer a theoretical solution to the problem of protective immunity and its duration. We also note that in order to quantitatively determine the studied parameters in a homogenous population group, it is necessary to know 5 parameters of the bivariate probability density function for correlated continuous random variables: the infective dose of the pathogen and the antibody titer at which the disease develops and which are still unknown.Copyright © Extreme Medicine.All right reserved.
RESUMEN
COVID-19 belongs to the group of acute respiratory infections and it is often complicated with pneumonia. This study aimed to investigate manifestations of community-acquired pneumonia (CAP) epidemic process during the COVID-19 epidemic in the Russian Federation. We analyzed the official statistical data reporting the incidence of CAP in the Russian Federation in 2013-2020 and incidence of COVID-19 as registered in March-July 2020. The mean average annual CAP incidence rate that we calculated and the 2020 CAP incidence prediction allowed assessing the relationship between CAP and COVID-19. It is shown that the long-term dynamics of the incidence of CAP in the Russian Federation is characterized by a pronounced upward trend with an average annual growth rate of 6.4%. The share of adult population among the CAP cases is the largest;on average, it is 64.7% (95% CI [63.1;66.3]). In 2020, against the background of SARS-CoV-2 circulation, the discrepancy between the actual incidence of CAP and the predicted figures reached and exceeded 558% (in July 2020). As the COVID-19 epidemic developed, the incidence of CAP was registered to increase. There was established a direct and significant correlation between the incidence of CAP and COVID-19 (rxy = 0.932;p <0.01).Copyright © 2022 Obstetrics, Gynecology and Reproduction. All rights reserved.
RESUMEN
Systemic vaccination against SARS-CoV-2 elicited high titers of specific antibodies in the blood and in the oral cavity. Preexisting autoimmune diseases, such as rheumatoid arthritis, and biological treatments, like B cell depletion, are known to exhibit higher risk of severe COVID-19 manifestation and increased frequency of breakthrough infections after vaccination. We hypothesized that such increased risk is associated with an aberrant induction of secreted antibodies in the oral cavity. Here we evaluated the levels of secreted antibodies in the oral cavity against the SARS-CoV-2 Spike protein during the course of vaccination in RA patients with or without B cell depletion. We found that total salivary IgG levels were correlated with number of B cells in the blood. Anti-Spike IgG responses 7 days after second vaccination were induced in the oral cavity of all healthy individuals, while only 6 out 23 RA patients exhibited anti-Spike IgG in their saliva regardless of B cell depleting therapy. Importantly, both salivary and serologic anti-Spike IgG and IgA responses towards WT and omicron Spike variants were efficiently induced by third vaccination in RA patients with or without B cell depletion to the levels that were similar to healthy individuals. Altogether, these data advocate for the necessity of three dose vaccination for RA patients to mount anti-Spike antibody responses at the mucosal surfaces and annotate the reduction of secreted salivary IgG by B cell depletion.