Will Invisible Omicron replace the original strain?

2022-05-07 0 By

In recent weeks, more and more cases of ba.2, a subtype variant of the omicron strain, have been reported in many countries. What is the nature of the “invisible omicron” variant?Will it replace the original Omicron strain and sweep the world?The genetic lineage name of the Omicron strain is B.1.1.529, and this variant strain was first identified in South Africa on 9 November 2021.On 26 November of the same year, THE World Health Organization classified B.1.1.529 as a variant strain of “concern”, named after the Greek letter Omicron (O).According to the WHO website, the Omicron strain includes the B.1.1.529 lineage and its descendants, ba.1, BA.1.1, BA.2 and BA.3.The evidence that the omicron strain is of “concern” is based on the genetic sequence of BA.1, which accounts for the vast majority of omicron infections worldwide to date.However, the number of cases of infection with the BA.2 strain, which has several different mutations from the BA.1 genome, is increasing in many countries.According to Pango, the international public platform for the classification and naming of novel Coronavirus genetic lineages, the genome of the BA.2 strain was first discovered in a sample submitted on 27 November 2021 to the Global Initiative for Influenza Data Sharing platform, which was collected on 17 November 2021 from Gauteng Province, South Africa.India, South Africa, The United Kingdom, Denmark and other countries are increasing their share of infections with the BA.2 strain, according to a WHO report released Monday.According to foreign media reports, since November 17, 2021, about 40 countries and regions have submitted nearly 15,000 genome sequences of the BA.2 strain to the Global Initiative for Influenza Data Sharing.The Ba.2 strain is rapidly replacing the BA.1 strain in the country, according to a communique issued by the Danish National Serum Institute on The 20th.In the last week of 2021, the BA.2 strain accounted for 20% of all confirmed COVID-19 cases in Denmark, rising to 45% by the second week of 2022.The BA.2 strain has been identified by the HEALTH and Safety Agency as a “mutant strain under investigation (VUI)”, according to a statement issued by the AGENCY on Monday.As of Monday, more than 400 cases of the BA.2 strain have been confirmed in the UK by whole genome sequencing.The earliest case detected in the country to date dates back to 6 December 2021.Ba.1 remains the dominant strain circulating in the UK and the proportion of CASES of BA.2 infection is currently very low.The propagation ability and other characteristics of BA.2 are being studied and analyzed, but are not clear so far.According to WHO, the vast majority of the omicron strain’s genetic sequence carries a mutation in which a spike protein gene segment is missing, and screening for this specific mutation can quickly distinguish omicron infection from other mutated COVID-19 strains.However, the ba.2 genome does not have this missing gene segment, which would have prevented it from being detected by routine screening for omicron infection, earning it the nickname “invisible Omicron”.The HEALTH and Safety Agency said it did not know what impact the changes to the ba.2 genome would have.Preliminary evidence suggests that the number of infections in BA.2 may be increasing at a faster rate than in BA.1.There is not enough evidence to determine whether BA.2 causes more severe disease than BA.1.In the opinion of the Danish National Serum Institute, preliminary analysis showed that ba.2 and BA.1 strains did not differ in the rate of hospitalization of patients.(Reporter Luo Guofang) (Xinhua)