Near complete genome sequences from Southern Vietnam revealed local features of genetic diversity and intergenerational changes in SARS- CoV-2 variants in 2020-2021.

BACKGROUND: Since its beginnings in 2019, the COVID-19 pandemic is still a problem of global medical concern. Southern Vietnam is one of the country's vast regions, including 20 provinces and the densely populated metropolis Ho Chi Minh City. A randomized retrospective study was performed to investigate the epidemiology and genetic diversity of COVID-19. Whole-genome sequencing of 126 SARS-CoV-2 samples collected from Southern Vietnam between January 2020 and December 2021 revealed the main circulating variants and their distribution. METHODS: Epidemiological data were obtained from the Department of Preventive Medicine of the Vietnamese Ministry of Health. To identify circulating variants, RNA, extracted from 126 nasopharyngeal swabs of patients with suspected COVID-19 were sequenced on Illunina MiSeq to obtain near complete genomes SARS-CoV-2. RESULTS: Due to the effectiveness of restrictive measures in Vietnam, it was possible to keep incidence at a low level. The partial relaxation of restrictive measures, and the spread of Delta lineages, contributed to the beginning of a logarithmic increase in incidence. Lineages 20A-H circulated in Southern Vietnam during 2020. Spread of the Delta lineage in Southern Vietnam began in March 2021, causing a logarithmic rise in the number of COVID-19 cases. CONCLUSIONS: Pandemic dynamics in Southern Vietnam feature specific variations in incidence, and these reflect the success of the restrictive measures put in place during the early stages of the pandemic.

Comparative Analysis of Library Preparation Approaches for SARS-CoV-2 Genome Sequencing on the Illumina MiSeq Platform.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been responsible for over two years of the COVID-19 pandemic and a global health emergency. Genomic surveillance plays a key role in overcoming the ongoing COVID-19 pandemic despite its relative successive waves and the continuous emergence of new variants. Many technological approaches are currently applied for the whole genome sequencing (WGS) of SARS-CoV-2. They differ in key stages of the process, and they feature some differences in genomic coverage, sequencing depth, and in the accuracy of variant-calling options. In this study, three different protocols for SARS-CoV-2 WGS library construction are compared: an amplicon-based protocol with a commercial primer panel; an amplicon-based protocol with a custom panel; and a hybridization capture protocol. Specific differences in sequencing depth and genomic coverage as well as differences in SNP number were found. The custom panel showed suitable results and a predictable output applicable for the epidemiological surveillance of SARS-CoV-2 variants.

Uninvited Guest: Arrival and Dissemination of Omicron Lineage SARS-CoV-2 in St. Petersburg, Russia.

Following its emergence at the end of 2021, the Omicron SARS-CoV-2 variant rapidly spread around the world and became a dominant variant of concern (VOC). The appearance of the new strain provoked a new pandemic wave with record incidence rates. Here, we analyze the dissemination dynamics of Omicron strains in Saint Petersburg, Russia's second largest city. The first case of Omicron lineage BA.1 was registered in St. Petersburg on 10 December 2021. Rapid expansion of the variant and increased incidence followed. The peak incidence was reached in February 2022, followed by an observed decline coinciding with the beginning of spread of the BA.2 variant. SARS-CoV-2 lineage change dynamics were shown in three categories: airport arrivals; clinical outpatients; and clinical inpatients. It is shown that the distribution of lineage BA.1 occurred as a result of multiple imports. Variability within the BA.1 and BA.2 lineages in St. Petersburg was also revealed. On the basis of phylogenetic analysis, an attempt was made to trace the origin of the first imported strain, and an assessment was made of the quarantine measures used to prevent the spread of this kind of infection.