Prevalence of arvi, influenza, and COVID-19 pathogens in individuals without symptoms of respiratory infection

Introduction. SARS-CoV-2 can be transmitted by infected people without or with mild symptoms of acute respiratory infection (ARI). Monitoring based on nucleic acid amplification techniques is used to measure the prevalence of ARI pathogens and to assess the effectiveness of preventive measures. The aim is to measure the prevalence of pathogens causing ARIs of viral etiology, influenza, and COVID-19 among individuals without ARI symptoms throughout age groups, to trace changes in the epidemic situation by weekly monitoring pathogens during the inter-epidemic period and at the beginning of a typical ARI epidemic season, to assess the effectiveness of medical masks for prevention of the above infections. Materials and methods. A total of 14,119 people (including 4,582 children) without ARI symptoms went through examination, including questionnaire surveys, in 26 regions of Russia from August to October 2020. Nasopharyngeal and oropharyngeal swabs were tested by using AmpliSens ARVI-screen-FL, AmpliSens Influenza virus A/B-FL, and AmpliSens Cov-Bat-FL reagent kits (The Central Research Institute of Epidemiology of Rospotrebnadzor, Moscow). Results. 11.1% of the tested samples showed positive results;the rhinovirus prevailed (7.32%), while SARS-CoV-2 was detected in 1.66%. In autumn, the proportion of SARS-CoV-2 infected cases increased from 0.49% to 4.02% (p < 0.001). The SARS-CoV-2 RNA concentration was up to 1010 copies/mL. Conclusions. Differences in the prevalence of SARS-CoV-2 and rhinovirus among the age groups and over time were found and analyzed. Using of medical masks reduced the risk of infection with respiratory viruses and with SARS-CoV-2 by 51% and 34%, respectively. In case of prolonged exposure to a COVID-19 patient, healthy people must use a respirator for more effective protection. The individuals whose work was associated with a high level of social contacts were infected more rarely than other individuals in the same age group (p = 0.001);this fact supports the importance of anti-epidemic measures and commitment to their adherence by people whose profession entails frequent social contacts. © 2021, Central Research Institute for Epidemiology. All rights reserved.

[Analysis of human coronaviruses circulation].

INTRODUCTION: The novel SARS-CoV-2 coronavirus, which emerged at the end of 2019 and caused a worldwide pandemic, triggered numerous questions about the epidemiology of the novel COVID-19 disease and  about wellknown coronavirus infections, which used to be given little attention due to their mild symptoms. THE PURPOSE: The routine screening-based multiyear retrospective observational study of prevalence and circulation patterns of epidemic-prone human coronaviruses in Moscow. MATERIAL AND METHODS: The real-time polymerase chain reaction was used to detect RNA of human coronaviruses (HCoVs) in nasal and throat swabs from 16,511 patients with an acute respiratory infection (ARI), aged 1 month to 95 years (children accounted for 58.3%) from January 2016 to March 2020, and swabs from 505 relatively healthy children in 2008, 2010 and 2011. Results. HCoVs were yearly found in 2.6-6.1% of the examined patients; the detection frequency was statistically higher in adults than in children, regardless of sex. At the height of the disease incidence in December 2019, HCoVs were detected in 13.7% of the examined, demonstrating a two-fold increase as compared to the multi-year average for that month. The statistical frequency of HCoV detection in ARI pediatric patients under 6 years was significantly higher than in their healthy peers (3.7 vs 0.7%, p = 0.008). CONCLUSION: HCoVs circulate annually, demonstrating a winter-spring seasonal activity pattern in the Moscow Region and reaching peak levels in December. Over the years of observation, the HCoV epidemic activity reached maximum levels in December 2019-February 2020 and decreased in March to the multi-year average. Amid a growing number of SARS-CoV-2 cases imported to Moscow in March 2020, the HCoV detection frequency dropped sharply, which can be explained by the competition between different coronaviruses and by the specificity of HCoV detection with the diagnostic test kit used in this study.

Gender-age distribution of patients with COVID-19 at different stages of epidemic in Moscow

The ongoing COVID-19 pandemic around the world and in Russia remains a major event of 2020. All over the world, research is being conducted to comprehensively study the patterns and manifestations of the epidemic process. The main quantitative characteristics of SARS-CoV-2 transmission dynamics among the population, based on the data of official monitoring over the current situation, play an important role in the development of the epidemiological surveillance system. The aim of this study is to explore the peculiarities of age-gender distribution of COVID-19 patients in Moscow. Material and methods. The data related to the epidemiological characteristics of age-gender structure of COVID-19 patients in Moscow between March 19, 2020 and April 15, 2020, at different stages of the epidemic were retrospectively analyzed. Results and discussion. The mean age of COVID-19 patients in Moscow was 46,41±20,58 years. The gender ratio (male/female) among the patients was 52.7/47.3 %, wherein the indicators varied depending upon the age. Male/female ratio in the age group “under 39” stood at 53.7/46.3 %, and “over 40 years of age” – at 39.3/60.7 %. The predominant age range among male cases was 19 to 39 years old – 35.4 %, while among female patients – 40–59 years (36.5 %). The age distribution of patients in Moscow is indicative of the fact that COVID-19 is a disease that primarily affects older age groups. The age structure of all COVID-19 cases during the observation period is characterized by predominance of adult patients over 19 years of age – 92,7 % (92,6–92,8 %), the share of patients aged 40–59 years is 35,7% (35,5–35,9 %). The differences in the age distribution in males and females are as follows: in the male cohort, the age groups 19–39 years old and 40–59 years old prevail – 35.4 % (35.1–35.7 %) and 34.9 % (34.6–35.2 %), respectively. The age group 40–59 years old – 36.5 % (36.3–36.8%) dominates in the female cohort. © 2020 Russian Research Anti-Plague Institute. All rights reserved.

[Patterns of the SARS-CoV-2 epidemic spread in a megacity].

The purpose of the study is to analyze patterns demonstrated by the COVID-19 epidemic process in a megacity during the increase, stabilization and reduction in the incidence, and to evaluate the effectiveness of the epidemic prevention measures. MATERIALS AND METHODS: The comprehensive study incorporating epidemiological, molecular genetic and  statistical research methods was conducted to analyze the spread of SARS-CoV-2 in Moscow during the COVID- 19 pandemic. RESULTS AND DISCUSSION: It was found that the exponential growth in COVID-19 cases was prevented due to the most stringent control and restrictive measures deployed in Moscow to break the chains of SARS-CoV-2 transmission and due to people who were very disciplined in complying with the self-isolation rules. The  analysis of the dynamics in detection of new COVID-19 cases showed that in a megacity, the impact of social distancing and self-isolation would become apparent only after 3.5 incubation periods, where the maximum length of the period is 14 days. It was discovered that the detection frequency of SARS-CoV-2 RNA in relatively healthy population and its dynamics are important monitoring parameters, especially during the increase and stabilization in the COVID-19 incidence, and are instrumental in predicting the development of the epidemic situation within a range of 1-2 incubation periods (14-28 days). In Moscow, the case fatality rate was 1.73% over the observation period (6/3/2020-23/6/2020). CONCLUSION: The epidemiological analysis of the COVID-19 situation in Moscow showed certain patterns of the SARS-CoV-2 spread and helped evaluate the effectiveness of the epidemic prevention measures aimed at  breaking the routes of transmission of the pathogen.