Updated April 21, 2023 at 9:00 am
National Institute of Infectious Diseases, Japan
*This is a provisional translation of the summary of the report entitled "kansen-denpasei no zoukaya kougenseino henkaga kenensareru SARS-CoV-2 no henikabunituite (dai27hou) (https://www.niid.go.jp/niid/ja/2019-ncov/2551-cepr/11879-sars-cov-2-27.html)". In the case of any dispute over translation, Japanese text prevails.
Overview of SARS-CoV-2 variants
The Omicron variant, along with its B.1.1.529 lineage and descendant sub-lineages, remains dominant globally among SARS-CoV-2 variants, and there have been no significant changes in epidemiological trends since the No. 26 report. Several sub-variants and recombinant omicron variants have been reported. The WHO has classified XBB.1.5 as a currently circulating variant of interest (VOI) and BA.2.75, CH.1.1, BQ.1, XBB, XBB.1.16, XBB.1.9.1, and XBF as currently circulating variants under monitoring (VUMs) since April 12, 2023.
However, there were no significant changes in viral characteristics, such as severity and infectivity/transmissibility, apart from an increase in the number of infected cases and the possibility of immune escape between subvariants. Thus, NIID continues to classify the subvariants as before. It is important to continue monitoring and collecting information on subvariant outbreaks through genomic analysis in the country and quarantine.
According to the WHO weekly epidemiological updates on COVID-19 (April 13, 2022), 47.9% of XBB.1.5 sequences, 7.6% of XBB.1.9.1 and 17.6% of the other XBB variant (excluding XBB.1.5, XBB.1.16, and XBB.1.9.1) were reported in the 12th week of 2023 (March 20-26, 2023).
In Japan, BA.5 replaced BA.2 around July 2022, and the relative sequence prevalence among circulating variants has been dominated by BA.5, followed by an increasing proportion of BQ.1 (a sub-lineage of the BA.5.3 lineage) and BA.2.75 (a sub-lineage of the BA.2 lineage) since October 2022. The proportion of XBB variants has increased since January 2023.
Some subvariants, such as BQ.1 and XBB, exhibit characteristic mutations in the spike protein that allow the virus to evade neutralizing antibodies generated through vaccination or previous infection and may have a growth advantage. Some subvariants, such as XBB.1.5 in North America, XBB.1.9 in Europe, and XBB.1.16 in India, may have a growth advantage over existing sub-lineages in certain regions. However, there is no evidence that these variants spread more rapidly than other variants.
Omicron sub-variants have emerged with specific characteristics that primarily contribute to immune escape. There were no significant differences compared with the other variants, except for this feature. Global immunity and several public health interventions in each country have resulted in less of an impact of the variant-specific nature on epidemic dynamics. Regular monitoring of variant prevalence and changes in variant-specific features, including pathogenicity, virulence, transmissibility, vaccine and antiviral resistance, and clinical presentation, is crucial for determining appropriate interventions and rapid risk assessment for each variant.
Updated March 24, 2023, at 9:00 am
National Institute of Infectious Diseases, Japan
*This is a provisional translation of the summary of the report entitled "kansen-denpasei no zoukaya kougenseino henkaga kenensareru SARS-CoV-2 no henikabunituite (dai26hou) (https://www.niid.go.jp/niid/ja/2019-ncov/2551-cepr/11879-sars-cov-2-26.html)". In the case of any dispute over translation, Japanese text prevails.
Overview of SARS-CoV-2 variants
The Omicron, the B.1.1.529, and its descendent lineages are still dominant globally among SARS-CoV-2 variants, with no significant changes in epidemiological trends compared to the No. 25 report. The World Health Organization (WHO) refers to all B.1.1.529 sub-lineages and recombinants as Omicron, whereas NIID has classified omicron variants as variants of concern (VOCs).
The omicron variants are genetically divergent, and WHO and European Centre for Disease Prevention and Control (ECDC) have classified them as variants under monitoring (VUM), variants of interest (VOIs), and VOCs. The WHO has classified XBB.1.5 as currently circulating variants of interest (VOIs), and BQ.1, BA.2.75, CH.1.1, XBB and XBF as currently circulating variants under monitoring (VUMs), respectively, since March 15. However, the information lacks significant changes in viral characteristics such as severity or infectivity/transmissibility, apart from the predominance of the increased number of infected cases and the possibility of immune escape between subvariants. Thus, NIID continues the current classification of the subvariants. It is important to continue monitoring and collecting information on sub-variant outbreaks through genomic analysis in the country and quarantine.
They accounted for 98.4% of the sequences submitted to GISAID from February 13 to March 13, with few reports of other lineages (WHO, 2023). The XBB variant accounted for 44.8% of the detected subvariants and became dominant in five of the six WHO regions, except the Western Pacific region, in the 8th week of 2023 (February 20-26).
The top three variants globally were XBB.1.5 (35.1%), BQ.1 (15.1%), and XBB, excluding XBB.1.5 (9.7) (WHO, 2023). In Japan, BA.5 replaced BA.2 around July 2022, and the relative sequence prevalence among circulating variants has been dominated by BA.5, followed by an increasing proportion of BQ.1 (a sub-lineage of the BA.5.3 lineage) and BA.2.75 (a sub-lineage of the BA.2 lineage) since October 2022.
Some subvariants, such as BQ.1 and XBB, exhibit characteristic mutations in the spike protein that allow the virus to evade neutralizing antibodies through vaccination, infection, and/or show a growth advantage. Some subvariants, such as XBB.1.5, are increasing in North America and may have a growth advantage over existing sub-lineages in certain regions. However, there were no findings that they spread more rapidly than the other variants.
Omicron subvariants have emerged with specific characteristics that primarily contribute to immune escape. There were no significant differences from the other variants except for them. Global immune status and some public health interventions in each country have resulted in less influence of variant-specific nature on epidemic dynamics. It is crucial to determine appropriate interventions based on regular monitoring of variant prevalence and changes in variant-specific features, including virulence, transmissibility, vaccine and antiviral resistance, clinical presentation, and rapid risk assessment for each variant.
COVID-19 surge has been reported in China since November 2022. China decided to cease the zero-COVID-19 policy on December 7, 2022. The number of daily cases started increasing in late December 2022, and there was a late increase in severe or hospitalized patients in early January 2023. Recent reports have demonstrated a decreasing trend in the number of daily cases. According to sequences submitted to GISAID from China, BA.5.2.48 and BF.7.14 were considered dominant. These subvariants are thought to have no significant effect on immune escape, transmissibility, and severity compared with BA.5.2 and BF.7, which have already been detected in Japan.
Japan conducted screening tests for all passengers with a travel history of China (excluding Hong Kong and Macau) (within seven days) and all passengers directly from China (excluding Hong Kong and Macau) as they arrived from December 30, 2022. These test results revealed that BA.5.2 and BF.7 are dominant in these passengers from China. The quarantine testing policy has changed since March 1 to test a maximum of 20% of the samples from passengers from China (excluding Hong Kong and Macau).
Updated February 10, 2023, at 9:00 am
National Institute of Infectious Diseases, Japan
*This is a provisional translation of the summary of the report entitled "kansen-denpasei no zoukaya kougenseino henkaga kenensareru SARS-CoV-2 no henikabunituite (dai25hou) (https://www.niid.go.jp/niid/ja/2019-ncov/2551-cepr/11749-sars-cov-2-25.html)". In the case of any dispute over translation, the Japanese text prevails.
Overview of SARS-CoV-2 variants
The Omicron, the B.1.1.529 lineage and its descendent lineages are still dominant globally among SARS-CoV-2 variants with no significant changes in epidemiological trends compared to the No. 24 report. They accounted for 99.9% of sequences submitted to GISAID from December 30, 2022, to January 30, 2023, with few reports of other lineages (WHO, 2023a). Among Omicron descendent lineages, BA.5 and its descendent lineages remain dominant, followed by BA.2 and BA.4 (including their descendent lineages), accounting for 65.7%, 14.6%, and 0.3%, respectively, of sequences, reported globally during epidemiological week 2, from January 9 to 15, 2023 (WHO, 2023a). The top three variants globally in January 2023 were BQ.1.1 (28.2%), BQ.1 (14.1%), and XBB.1.5 (11.5%) (WHO, 2023a). In Japan, BA.5 replaced BA.2 around July 2022, and relative sequence prevalence among circulating variants has been dominated by BA.5, followed by the increasing proportion of BQ.1 (a sub-lineage of the BA.5.3 lineage) and BA.2.75 (a sub-lineage of the BA.2 lineage) since October 2022. The World Health Organization (WHO) refers to all B.1.1.529 sub-lineages and recombinants as Omicron, while several sub-lineages and recombinants (BF.7, BQ.1, BA.2.75, and XBB) as "Omicron subvariants under monitoring" since January 13, 2023.
Some subvariants, such as BQ.1 and XBB, exhibit characteristic mutations in the spike protein that allow the virus to evade neutralizing antibodies through vaccination, infection, and/or show growth advantage. Some subvariants, such as XBB.1.5, are increasing in North America and may have a growth advantage over existing sub-lineages in certain regions. However, there are no findings that they spread rapidly compared to other variants.
Omicron subvariants have emerged with specific characteristics that primarily contribute to immune escape. There are no significant differences from other variants except for them. Global immune status and some public health interventions in each country have resulted in less influence of variant-specific natures on epidemic dynamics. It is crucial to determine appropriate interventions based on regular monitoring of variant prevalence and changes in variant-specific features, including virulence, transmissibility, vaccine and antiviral resistance and clinical presentation, and rapid risk assessments for each variant.
COVID-19 surge has been reported in China since November 2022. China has decided to cease the zero-COVID-19 policy on December 7, 2022. The number of daily cases started increasing in late December 2022, and then there was a late increase in the number of severe or hospitalized patients in early January 2023. Recent reports show a decreasing trend in the number of daily cases. According to sequences submitted to GISAID from China, BA.5.2 and BF.7 are considered dominant, which have already been detected in Japan. Japan has been conducting screening tests for all passengers who have a travel history of China (excluding Hong Kong and Macau) (within seven days) and all passengers directly from China (excluding Hong Kong and Macau) as they arrive since December 30, 2022. These test results have revealed that BA.5.2 and BF.7 are dominant in these passengers from China. The number of passengers to or from China during and around the Lunar New Year in late January is expected to increase, and besides, this trend would be driven by easing travel restrictions for citizens by the China Government. Thus, it is crucial to monitor the situation in China carefully.
Updated January 13, 2023 at 9:00 am
National Institute of Infectious Diseases, Japan
*This is a provisional translation of the summary of the report entitled "kansen-denpasei no zoukaya kougenseino henkaga kenensareru SARS-CoV-2 no henikabunituite (dai24hou)(https://www.niid.go.jp/niid/ja/2019-ncov/2551-cepr/11749-sars-cov-2-24.html)".
In the case of any dispute over translation, the Japanese text prevails.
Overview of SARS-CoV-2 variants
The Omicron, the B.1.1.529 lineage and its descendent lineages are still dominant globally among SARS-CoV-2 variants with no significant changes in epidemiological trends compared to the No 23 report. They accounted for 98.4% of sequences submitted to GISAID from December 2, 2022, to January 2, 2023, with few reports of other lineages (WHO, 2023a). Among Omicron descendent lineages, BA.5 and its descendent lineages remain dominant, followed by BA.2 and BA.4 (including their descendent lineages), accounting for 63.7%, 15.2%, and 0.7%, respectively, of sequences, reported globally during epidemiological week 50, from December 12 to 18 2022 (WHO, 2023). In Japan, BA.5 replaced BA.2 around July 2022, and relative sequence prevalence among circulating variants has been dominated by BA.5, followed by the increasing proportion of BQ.1 (a sublineage of the BA.5.3 lineage) and BA.2.75 (a sub-lineage of the BA.2 lineage) since October 2022. Various recombinant variants among Omicron descendent lineages have been reported as well. The World Health Organization (WHO) refers to all B.1.1.529 sub-lineages and recombinants as Omicron, while several sub-lineages and recombinants (BF.7, BQ.1, BA.2.75, and XBB) and BA.5 with one or several mutations (S:R346X, S:K444X, S:V445X, S:N460X), as "Omicron subvariants under monitoring" since January 13, 2023.
Some subvariants, such as BQ.1 and XBB (a recombinant of BJ.1 [a sub-lineage of BA.2.10] and BM.1.1.1 [a sub-lineage of BA.2.75.3]), exhibit characteristic mutations in the spike protein that allow the virus to evade neutralizing antibodies through vaccination, infection, and/or show the growth advantage. XBB.1.5, a recombinant lineage, is increasing in North America and may have a growth advantage over existing sub-lineages in certain regions. However, there are no findings that they spread rapidly compared to other variants.
Omicron subvariants have emerged with specific characteristics that primarily contribute to immune escape. There are no significant differences from other variants except for them. Global immune status and some public health interventions in each country have resulted in less influence of variant-specific natures on epidemic dynamics. It is crucial to determine appropriate interventions based on regular monitoring of variant prevalence and changes in variant-specific features, including virulence, transmissibility, vaccine and antiviral resistance and clinical presentation, and rapid risk assessments for each variant.
COVID-19 surge has been reported in China since November 2022. China has decided to cease the zero-COVID-19 policy on December 7, 2022. The number of daily cases started increasing in late December 2022, and then there was a late increase in the number of severe or hospitalized patients in early January 2023. Recent reports show a decreasing trend in the number of daily cases. According to sequences submitted to GISAID from China, BA.5.2 and BF.7 are considered dominant, which have already been detected in Japan as well. Currently, passengers arriving in Japan from China have to provide a negative Covid test before they board a flight, and Japan has been conducting screening tests for all passengers who have a travel history of China (excluding Hong Kong and Macau) (within seven days) and all passengers directly from China (excluding Hong Kong and Macau) as they arrive since December 30, 2022. These test results have revealed that BA.5.2 and BF.7 are dominant in these passengers from China. The number of passengers to or from China during and around the Lunar New Year in late January is expected to increase, and besides, this trend would be driven by easing travel restrictions for citizens by the China Government. Thus, it is crucial to monitor the situation in China carefully.