Structure of herd immunity to SARS-COV-2 in the Krasnoyarsk region population in the COVID-19 epidemic

Purpose. Determination of the SARS-CoV-2 population humoral immunity among the population of the Krasnoyarsk Territory during the COVID-19 epidemic.Materials and methods. The study was carried out as a part of project for assessing population immunity to SARS-CoV-2 among the population of Russian Federation using unified methodology developed by Rospotrebnadzor, with the participation of the Research Institute for Epidemiology and Microbiology named by Pasteur, and taking into account the recommendations of the WHO. The work involved 2907 volunteers, selected by the online survey and randomization by age and territory. All volunteers were divided into 7 age groups: 1–17, 18–29, 30–39, 40–49, 50–59, 60–69, 70 and older (70+), including a total 246–449 people. Population immunity testing was carried out during the formation of groups (1st stage), and then twice more, with the interval of 6–8 weeks. Serum was obtained from venous blood samples obtained from volunteers, in which antibodies to the SARS-CoV-2 nucleocapsid were determined by the enzyme immunoassay. The results were analyzed by methods of nonparametric statistics: median, interquartile range, rank correlation coefficient were calculated in the Excel statistical package. The confidence interval to seroprevalence indicators (95% CI) was calculated using the WinPepi statistical package (version 11.65). The statistical significance of the differences was assessed with a probability level of p ≤ 0.05.Results. The seroprevalence of the population of the Krasnoyarsk Territory during the 5-month period of seromonitoring had increased 3.3 times from 12.8% (95% CI 11.3–14.4) to 41.7% (95% CI 39.4–4.0) , while the grouping by age had not revealed any peculiarities throughout the study. The trend towards a decrease in the incidence was formed on the 6th week of 2021. The seroprevalence of convalescents after COVID-19 during the initial testing was 61.5% (95% CI 40,6–79.8), among those who were in contact with patients with COVID-19 or convalescents –23.8% (95% CI 13.9–36.2) . Among the volunteers, 347 seropositive persons were identified, 324 of which were observed asymptomatic course.Conclusion. The structure of the population humoral immunity to SARS-CoV-2 of he population of the Krasnoyarsk Territory has been investigated. It was found that an increase in seroprevalence to 41.7% (95% CI 39.4–4.0) was accompanied by a decrease in morbidity

Характеристика популяционного иммунитета среди населения Ставропольского края на фоне эпидемии COVID-19

Introduction. The first pandemic in the 21st century, caused by the pathogenic representative of the coronavirus SARS-CoV-2, began in the Chinese city of Wuhan, where the first outbreak of coronavirus pneumonia was recorded in December 2019. The disease spread so quickly around the world that already on February 11, 2020, WHO was forced to declare a pandemic of the “coronavirus disease 2019” COVID-19. The first case of COVID-19 in the Stavropol Territory was registered on March 20, 2020, and three weeks later, starting from the 15th week of the year, a steady increase in the incidence began, which lasted until the 52nd week. During the study period, the incidence increased from 21.1 to 28.3 per hundred thousand of the population. Growth 1.3 times.Purpose: to determine the dynamics of population immunity among the population of the Stavropol Territory in 2020-2021. during the period of an epidemic increase in the incidence of COVID-19. Materials and methods. The SARS-CoV-2 study was carried out according to a unified methodology within the framework of the program for assessing the population immunity of the population of the Russian Federation, developed by Rospotrebnadzor with the participation of the St. Pasteur. In total, 2688 people were examined, divided into 7 age groups. In the examined individuals, the level of specific IgG to the SARS-CoV-2 nucleocapsid was determined by the enzyme immunoassay.Results. The level of seroprevalence among residents of the Stavropol Territory was 9.8%. The largest proportion of seropositive individuals was found in the age groups 1-6 and 7-13 years old (19.2% and 19.7%, respectively). Seroprevalence had no gender differences and ranged from 9.3% to 10.8%. When assessing the distribution of the proportion of seropositive persons in different geographic territories of the region, it was found that the maximum proportion was found in the Kochubeevsky district (23.1%), the minimum in Kislovodsk (7.7%). Among convalescents, the content of specific antibodies to SARS-CoV-2 was noted in 73.3%, which is 7.8 times higher than the average population level. When conducting seromonitoring in the 2nd half of 2020, a 10-fold increase in seroprevalence was recorded, accompanied by a decrease in incidence from the 5th week of 2021. Among asymptomatic volunteers in whom SARS-CoV-2 RNA was detected by the polymerase chain reaction, antibody titers to viruses were found in 78.6%, which corresponds to the seroprevalence of convalescents. The proportion of seropositive persons among those who have come into contact with COVID-19 patients was 16.4%, (1.8 times higher than the average for the population). Out of 262 seroprevalent volunteers, the asymptomatic form of SARS-CoV-2 was detected in 92% of the examined, which indicates a significant role of the number of asymptomatic forms of infection in the epidemic process of COVID-19.Conclusion. The results of assessing the population immunity of the population of the Stavropol Territory indicate that it has not yet reached the threshold level at which a decrease in the intensity of the COVID-19 epidemic process can be expected. Введение. Первая в XXI в. пандемия, вызванная патогенным представителем коронавирусов SARS-CoV-2, началась в китайском городе Ухань, где в декабре 2019 г. была зарегистрирована первая вспышка коронавирусной пневмонии. Заболевание настолько быстро распространилось по миру, что уже 11 февраля 2020 г. ВОЗ была вынуждена объявить пандемию «коронавирусной болезни 2019 г.» COVID-19. Первый случай COVID-19 в Ставропольском крае был зарегистрирован 20 марта 2020 г., а через 3 недели, начиная с 15-й недели года, начался неуклонный рост заболеваемости, продолжавшейся до 52-й недели. В период проведения исследования заболеваемость выросла с 21,1 до 28,3 на 100 000 населения (рост в 1,3 раза).Цель: определить динамику популяционного иммунитета среди населения Ставропольского края в 2020– 2021 гг. в период эпидемического роста заболеваемости COVID-19.Материалы и методы. Исследование SARS-CoV-2 проведено по единой методике в рамках программы оценки популяционного иммунитета населения Российской Федерации, разработанной Роспотребнадзором при участии Санкт-Петербургского Научно-исследовательского института эпидемиологии и микробиологии им. Пастера. Всего обследовано 2688 человек, распределенных на 7 возрастных групп. У обследованных лиц определяли уровень специфического IgG к нуклеокапсиду SARS-CoV-2 иммуноферментным методом.Результаты. Уровень серопревалентности среди жителей Ставропольского края составил 9,8%. Наибольшая доля серопозитивных лиц выявлена в возрастных группах 1–6 и 7–13 лет (19,2% и 19,7% соответственно). Серопревалентность не имела гендерных различий и варьировала в пределах 9,3–10,8%. При оценке распределения доли серопозитивных лиц по разным географическим территориям края установлено, что максимальная доля выявлена в Кочубеевском районе (23,1%), минимальная – в Кисловодске (7,7%). Среди реконвалесцентов содержание специфических антител к SARS-CoV-2 отмечено в 73,3%, что в 7,8 раза выше среднепопуляционного уровня. При проведении серомониторинга во 2-й половине 2020 г. был зафиксирован 10-кратный рост серопревалентности, сопровождавшийся снижением заболеваемости с 5-й недели 2021 г. Среди бессимптомных волонтёров, у которых выявили РНК SARS-CoV-2 методом полимеразной цепной реакции, титры антител к вирусам найдены в 78,6%, что соответствует серопревалентности реконвалесцентов. Доля серопозитивных среди лиц, контактировавших с больными COVID-19, составила 16,4% (1,8 раза выше, чем в среднем по популяции). Из 262 серопозитивных волонтёров бессимптомная форма SARS-CoV-2 выявлена у 92% обследованных, что указывает на существенную роль числа бессимптомных форм инфекции на эпидемический процесс по COVID-19.Выводы. Результаты оценки популяционного иммунитета населения Ставропольского края свидетельствуют, что он пока не достиг порогового уровня, при котором можно ожидать снижения интенсивности эпидемического процесса COVID-19.

Mouse Brain Slice Segmentation for Analysis of Physiological Activity

In the paper we suggest an approach for preprocessing histological images of brain slices. These images are usually received in noisy environment and thus require sophisticated preprocessing. We present two algorithms for brain contour detection and use their results for further nucleus detection that is important for biologists. We test our methods on real mouse brain data and show their applicability

Hybrid Tamm-cavity modes in photonic crystal with resonant nanocomposite defect layer

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.Hybrid optical modes in a one-dimensional photonic crystal with a resonant nanocomposite defect bounded by a metallic layer are studied. The nanocomposite consists of spherical metallic constituents, that are distributed in a dielectric matrix. Transmittance, reflectance, and absorbance spectra of this structure, which is shined by light with normal incidence, are calculated. The possibility of control of the hybrid modes spectral characteristics by changing the thickness of the layer adjacent to the metal, the number of layers, and the nanocomposite filling factor is shown