JOURNAL OF BACTERIOLOGY AND VIROLOGY ISSN:1598-2467(Print) 2093-0429(Online)

As the coronavirus disease 2019 (COVID-19) spread worldwide, variants viruses are constantly emerging. And there has been a growing interest in the study of variant viruses, for the necessity of response to emergence and diffusion of new coronavirus variants. So, we conducted a survey of variant proportions of SARS-CoV-2 on positive samples of confirmed cases by Real-time Polymerase Chain Reaction (Real-time PCR). From December 26, 2021 to April 2, 2022, a total of 819 SARS-CoV-2 variants of concern (VOCs) were identified in COVID-19 positive samples. In the 2nd week of January 2022, detection rate of the Omicron subvariant BA.1 was 58.1%, overtaking Delta variant to become dominant type. However, in the 5th week of March, detection rate of another Omicron subvariant BA.2 was 75.9%, became dominant variant. These results imply that BA.1 was a dominant variant for two months and after that, omicron BA.1 was rapidly replaced by omicron BA.2. This research is valuable because it provided information which is helpful to response diffusion of new variants. Compared to Delta variant, a large number of mutations in the spike gene(S) of Omicron variant were detected. It raises concerns about changes in pathogenicity and transmissibility in new COVID variants. Therefore, we should develop new strategies against emergence and diffusion of SARS-CoV-2 variants throughout monitoring appearance of the new variants, analyzing the characteristics of new things. In this respect, the results of this research are useful because they offered good basic data for appreciating characteristics of new COVID variants by monitoring the emergence of Delta and Omicron variant.