Background: The high rate of infection with COVID-19 in patients worldwide and Europe, and mutation of viruses have led to the emergence of variants of SARS-CoV-2. On November 26, 2021, the SARS-CoV-2 B.1.1.529, or Omicron variant, was recognized as a new Variant of Concern (VOC). We hypothesized that the emergence of SARS-CoV-2 variants in Ukraine followed the prevalence of Delta and Omicron in Europe. To test this hypothesis, we performed a retrospective study to determine the prevalence of SARS-CoV-2 variants circulating among patients hospitalized at Lviv Regional Infectious Diseases Hospital (LRIDH) in 2022.

Methods: From January 2022 to October 2022, 994 LRIDH inpatients were PCR positive for COVID-19. From these positive samples, 225 were selected for further analysis by the randomization method. Samples represented three stages. Stage 1 positive samples included the months of January and February. Stage 2 samples included the months of July and August, and stage 3 samples were from October of 2022. The presence SARS-CoV-2 spike S371L/ S373P mutations (Omicron, B.1.1.529) and the presence of Spike T478K mutations (Delta, B.1.617.2) were determined using VirSNiP SARS-CoV-2 Spike S371L S373P and "VirSNiP SARS-CoV-2 Spike T478K (TIB MOLBIOL LightMix, Germany). Testing was performed at the virological reference laboratory of the Public Health Center in Kyiv city, Ukraine. Statistical analysis was conducted using Chi-square tests.

Results: For stage 1, (January and February 2022) 75 samples (33.3%) were examined. Of these, 54 (72%) were Omicron and 16 (21.3%) were Delta. No mutation was detected in 5 samples (6.7%) (Ct˃30). Omicron (without sub-lineage) was found in 17 samples (31.5%), BA.1 sub-lineage in 21 samples (38.9%), BA.2 sub -lineage 10 samples (18.5%), and in 6 samples (11.1%) BA.2/BA.3 sub-lineage. In stage 2, 142 samples (63.1%) were examined. Of these, 134 (94.4%) were Omicron, and for 8 (5.6%), no mutation was detected. Omicron BA.2 was identified in 128 (95.5%) of these samples. In stage 3, (October 2022) 8 samples (3.6%) were examined. All were Omicron and BA.5.1 was found in 3 samples (37.5%), BA.5.2 in 1 sample (12.5%), BA.5.2.1 in 2 samples (25%) and in 2 samples (25%) BA.5.2.6.

Conclusions:Studying the evolution of the SARS-CoV-2 virus and detecting its mutation makes it possible to predict the severity of the disease and the effectiveness of vaccination. The results are consistent with our hypothesis that in Ukraine, the prevalence of SARS-CoV-2 variants were consistent with Europe. The obtained results showed that the viruses circulating in Ukraine belong to the global genetic line B originating from China with a slight shift in time. In Ukraine, these tests can be performed routinely to assess the epidemiological situation and prevent the increase of the SARS-CoV-2 morbidity.