Analysis of the influence of age and location of contacts on the frequency of transmission of SARS-CoV2 in society

PURPOSE: Analysis of the frequency of transmission SARS-CoV2 in different age groups and locations allows to identify risks of transmission, influencing on the spread of COVID-19 in the population and to strengthen the control on pandemic METHODS & MATERIALS: Epidemiological analysis of contacts with primary cases of COVID-19 and secondary cases of infection for 6 months of 2020 in the different age groups was performed on the data of epidemiological surveillance system in 190,856 COVID-19 patients and 146,996 their contacts RESULTS: Patients with mild form of disease had the main proportion of contact - 50.6 %, moderate form - 45.8%. The proportion of contacts in patients with severe form was only 3.6%. Group aged 41-64 years had the highest number of cases (44.4%) and contacts (44,5%), aged 18-40 years - 30.2% of cases and 34.2% of contacts; 0-6 years - 2.7% of cases and 1,9% of contacts, 7-17 - 4,0 % of the cases and 3.1% of the contact. The number of contact persons was directly related to the number of secondary cases of the disease in all age groups: at the age of 0-6 years - 3.5 %, 7-17 years - 5,8 %, 18-40- 33,9%, 41-64 - 42,1%, 65 and older -14.7%. Patients of all age groups mainly contacted with healthy people in domestic focuses: the age group 0-17 years accounted for 65.9% of contacts, 18-40 years - 63.9%, 41-64 years - 64.2% over 65 years - 65.18%, respectively. The frequency of contacts at work was the highest at the age of 18-40 years – 9.0% and 41-64 years - 9.0%, but were significantly less than contacts in everyday (family) life - 63.8% and 64.2%, respectively. CONCLUSION: The most active transmission of infection is carried out by patients aged 18-64 years, carrying the disease in mild and moderate-severe form. Secondary transmission of COVID-19 most of all is active in household foci in all age groups. In the age groups of 18-64 years, the transmission of infection in the workplace is also important. These results of analysis can be used to optimize prevention measures against COVID-19.