[Analysis of human coronaviruses circulation]

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 routine screening-based multiyear retrospective observational study of prevalence and circulation patterns of epidemic-prone human coronaviruses in Moscow.

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).

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.