On January 4, the Ho Chi Minh City Tropical Diseases Hospital announced the results of variant screening for nCoV in 526 Covid patients, confirming the emergence of the XBB variant of Omicron, which is considered the “worst strain”.
XBB is the next-generation subvariant of the BA.2 Omicron strain, also known as BA.2.10. Scientists worldwide have deemed this subvariant of Omicron as “the worst variant to date” due to its ability to spread faster than any other subvariant, evade immunity from vaccines, natural infections, and monoclonal antibody treatments. Currently, there are no in-depth studies regarding the virulence of this new variant.
This is the first time Vietnam has reported the XBB variant.
This is the first time Vietnam has reported the XBB variant. Worldwide, scientists discovered this variant in August 2022, and it has spread to 70 countries over the past four months. According to the World Health Organization (WHO), XBB and its relative XBB.1.5 are responsible for 44% of infections in the United States, overshadowing other Omicron subvariants; leading to a new wave of infections in several regions of Asia, including India and Singapore in October 2022.
In Ho Chi Minh City, doctors at the Tropical Diseases Hospital, in collaboration with the Oxford University Clinical Research Unit (OUCRU), sequenced the virus genome of 526 Covid patients treated at the hospital from July 1, 2022, to December 25, 2022. The results showed that the Omicron variant dominated the city in the last six months of the previous year, with the Delta variant circulating in July 2022.
Specifically, from July to September 2022, the BA.5 Omicron subvariant was predominant; while in the last three months of the year, the BA.2.75 variant was the main strain. Additionally, there were three samples infected with the XBB variant. These samples came from three Covid-19 patients admitted in December 2022, indicating the new XBB variant’s entry.
Experts note a temporal shift among the Omicron subvariants in the city, aligning with global trends. The Delta variant was the dominant virus strain in Vietnam and worldwide in 2021, followed by the gradual prevalence of the Omicron variant due to its faster transmission and milder virulence. Since late 2021, Omicron has continuously produced multiple subvariants, including second and third-generation subvariants. XBB is the latest subvariant of Omicron.
Thus, with the emergence of XBB, it is highly likely that this new variant will dominate infections in the future. The Ho Chi Minh City Department of Health assesses that “the Covid-19 pandemic is still well-controlled,” partly due to the protective role of vaccines against severe cases and deaths. According to the pandemic prevention plan, the Ho Chi Minh City Tropical Diseases Hospital will continue to screen for nCoV variants in collaboration with OUCRU to assist the city in timely adjusting its pandemic response strategy.
Currently, the Ministry of Health does not have sequencing data available to assess the circulating nCoV variants nationwide.
