Discussion
sudden increase
EVENTS, EVENT, SAID
COVID-19 continues to be a pressing public health problem. Different countries have had varying levels of success in combating the COVID-19 pandemic, with some countries among the most successful in the world at containing the pandemic and others in serious jeopardy. In the East Asia and Pacific regions, the most successful are considered Singapore, New Zealand, South Korea, China, and Vietnam [Genomic surveillance for SARS-CoV-2 was announced by the WHO as a necessary measure for pandemic control. In June 2020, the WHO Virus Evolution Working Group was established with a specific focus on SARS-CoV-2 variants, their phenotype, and their impact on countermeasures [The Pasteur Institute in Ho Chi Minh City has shown vigilance and readiness in terms of monitoring SARS-CoV-2 lineages using NGS methods. According to the data obtained, it can be said that the first imported cases were from China and belonged to 19A (lineage B). Variants of lineage 19B (lineage A) circulated in Southern Vietnam from February to March 2020. In China, lineages A and B circulated together for a short time and were quickly totally replaced by lineage B [In addition to multiple introduced variants in 2020 [The beginning of the pandemic was marked by two major lineages, denoted ‘A’ and ‘B’, which are probably the result of two different spillover events. The first zoonotic transmission likely involved lineage B viruses and occurred from late-November to early-December 2019 (no earlier than early November 2019). Introduction of lineage A likely occurred within weeks of the first event [At the beginning of 2021, the Alpha and Beta variants (20I, 20H) continued circulation in Southern Vietnam. Like global COVID-19 pandemic trends, they were completely replaced by Delta lineages, followed by a sudden increase in incidence marking the beginning of the 4th pandemic wave in Vietnam. The Delta variant was represented by three phylogenetic lineages (21A, 21I, 21J), with the 21I lineage dominating. Intragenomic variability within the Delta lineage was observed as a set of synonymous and non-synonymous substitutions in addition to the defining ones.The first Delta variant sequences available in GISAID for ASEAN countries came from Malaysia [