China CDC analysis shows predominance of Omicron lineages BA.5.2 and BF.7 among locally acquired infections

The TAG-VE met on 3 January 2023 to discuss the COVID-19 situation in mainland China

The Technical Advisory Group on Virus Evolution (TAG-VE) meets regularly to review the latest scientific evidence on circulating SARS-CoV-2 variants and advises WHO on whether a change in public health strategies is warranted. The TAG-VE met on 3 January 2023 to discuss the COVID-19 situation in mainland China.

During the meeting, scientists from the China CDC presented genomic data from what they described as imported as well as locally-acquired cases of SARS-CoV-2 infections. For locally-acquired infections, data presented were based on more than 2000 genomes collected and sequenced from 1 December 2022. The China CDC analysis showed a predominance of Omicron lineages BA.5.2 and BF.7 among locally-acquired infections. BA.5.2 and BF.7 together accounted for 97.5% of all local infections as per genomic sequencing. A few other known Omicron sublineages were also detected albeit in low percentages. These variants are known and have been circulating in other countries, and at the present time no new variant has been reported by the China CDC.

As per WHO statement, “As of 3 January, 773 sequences from mainland China have been submitted to the GISAID EpiCoV database, with the majority (564 sequences) collected after 1 December 2022. Of those, only 95 are labeled as locally-acquired cases, 187 as imported cases and 261 do not have this information provided. Of the locally-acquired cases, 95 per cent belong to BA.5.2 or BF.7 lineages. This is in line with genomes from travellers from China submitted to the GISAID EpiCoV database by other countries. No new variant or mutation of known significance is noted in the publicly available sequence data.”

Acknowledging the information shared so far, the TAG-VE reiterated the critical need for and importance of additional analysis as well as sharing of sequence data to understand the evolution of SARS-CoV-2 and the emergence of concerning mutations or variants. This should be done regardless of whether a sequence is assigned a Pango lineage or not. This is best accomplished by rapid and regular depositing of data into publicly accessible databases. Maintaining high levels of representative genomic surveillance across China and globally, annotating genomic sequences with relevant clinical and epidemiological metadata, and rapid sharing of such data are the pillars of timely global risk assessment.

WHO says that it will continue to closely monitor the situation in the People’s Republic of China and globally and urged all countries to continue to be vigilant, to monitor and report sequences, as well as to conduct independent and comparative analyses of the different Omicron sublineages, including on the severity of disease they cause. At this time, the TAG-VE is also evaluating the rapidly increasing proportion of XBB.1.5 in the United States and other countries.