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Background. The COVID-19 pandemic has become a substantial global health crisis, unparalleled in world history. Infection dynamics can have specific characteristics in different countries due to social, economic, climatic, or geographic factors. Aim: to study features of SARS-CoV-2 collective immunity among the Armenian population. Materials and methods. A cross-sectional, randomized study of collective immunity was carried out according to a program developed by Rospotrebnadzor and the St. Petersburg Pasteur Institute, taking into account WHO recommendations. The study was approved by the ethics committees of the National Center for Infectious Diseases (Armenia) and the St. Petersburg Pasteur Institute (Russia). A volunteer cohort was formed (N = 6057), randomized by age and region. The studys analysis included: shares and distributions of antibodies (Abs) to nucleocapsid (Nc) antigen (Ag) and receptor binding domain (RBD) S-1 Ag in the cohort; and quantitative determination of these Abs by ELISA. During the survey, a history of vaccination was indicated by 4395 people. Results. Overall seropositivity formed in the whole cohort (by April 14, 2022) was 98.6% (95% CI: 98.198.7). It did not depend on age, place of residence, or occupation. When quantifying Nc and RBD Abs, the proportions of volunteers with Nc Ab levels of 117 BAU/ml and RBD Ab levels of 22.6220 BAU/ml were the smallest, amounting to 6.9% (95% CI: 6.27.5) and 20.4% (95% CI: 19.421.4), respectively. With increasing serum concentrations (Nc 667 BAU/ml, RBD 450 BAU/ml), the proportions of individuals with the corresponding levels were 20.2% for Nc (95% CI: 19.221.3) and 54.2% for RBD (95% CI: 52.955.5). Vaccination coverage was 72.6% (95% CI: 71.573.7). The most frequently used were Sinopharm/BIBP (32.4%), AZD1222 (22.3%), and Gam-COVID-Vac (21%). The remaining vaccines (CoronaVac, mRNA-1273, BNT162b2, CoviVac) were used by 24.3% of vaccinated individuals. When summing vaccines by platform, it was found that: vector vaccines were used in 40.34% (95% CI: 33.5742.39) of cases; whole-virion vaccines were used in 26.83% (95% CI: 24.7632.20); and vector vaccines were used in 6.33% (95% CI: 4.848.91). Conclusion. The epidemic situation in Armenia by April 2022 was characterized by a high level of collective immunity, independent of age or regional factors. Vector and whole-virion vaccines have been used most widely.

According to current data, SARS-CoV-2 virus has the ability to cause multi-organ pathology, leading to acute damage of various organs and systems and long-term consequences characterized by polymorphic symptoms. Recently, a high incidence of invasive mycoses, particularly mucormycosis COVID-M, has been noted among the COVID-19 complications. The predisposing factor for the development of this pathology is diabetes mellitus, immunodeficiency states, and prolonged use of high doses of glucocorticosteroids. Mucormycosis is characterized by severe clinical manifestations and high lethality, and timely diagnostics of this pathology often represents a difficult problem. The aim of this study was to analyze a clinical case of rhino-orbital mucormycosis in convalescent COVID-19 patient. In the study, there was used mucopurulent nasal discharge from the patient previously hospitalized with a severe novel coronavirus infection. Here, we describe the methodology allowing to isolate and identify a pure mold fungus culture from the biomaterial using methods of routine bacteriology and MALDI-ToF mass spectrometry. Direct microscopy examination of nasal cavity discharge revealed branched non-septic hyphae with a characteristic branching angle, allowing to preliminarily diagnose invasive mucormycosis. Growth of mycelial fungus colony was observed by using Sabourauds medium with potassium tellurite. Microscopy of the pure culture revealed branching mycelium without septa, broad, with irregular thickness, unsegregated hyphae, and sporangia with a typical column specific to mucormycetes. Analysis of the obtained mass spectra allowed to establish the microbial species identity as Lichtheimia corymbifera. The latter along with other members of the order Mucorales, are known to cause mucormycosis. As a result of antifungal treatment (Amphotericin B) and timely surgical intervention, the patient was discharged from the hospital with prominent clinical improvement and no complaints during further outpatient follow-up period. The analysis of this clinical case showed the lack of alertness in some clinical diagnostic laboratories to detect pathogens of invasive mycoses. To avoid errors, while making a diagnosis, attention should be paid not only to detection of fungal spores in clinical material, but also take into account the structure of mycelium underlying major difference between yeast-like fungi, higher and lower molds. The isolation and identification of a pure pathogen culture allows to confidently verify the diagnosis, timely correct the treatment tactics and monitor circulation of mycotic agents to prevent occurrence of mycoses in most vulnerable patients cohorts.