Views: 0 Author: Site Editor Publish Time: 2022-05-04 Origin: Site
It is generally believed that the new coronavirus Omicron strain is more contagious than other variants, but the severity of disease is less. But a large U.S. study published on the preprint platform "Research Square" on May 2 said that Omicron's "virulence" is not low, but is similar to what was previously thought. Just as serious as the previous variant.
The influence of Omicron is not over, and its series of variants BA.1, BA.2, BA.2.12.1, BA.4 and BA.5 are setting off a new wave of epidemics around the world. And the Delta variant does not seem to be reconciled to being stole the limelight by Omikron, and is quietly accumulating power and spreading it secretly, intending to "make a comeback".
BA.2.12.1 is "establishing a foothold" in the US
BA.2.12.1 is the descendant of the 2019-nCoV Omicron subtype variant BA.2, which is currently spreading rapidly in the United States.
According to US media reports, in February, two new, more contagious cases of the new coronavirus variant were identified in the northeastern United States. They are exactly the subtypes of the Ormicon strain variant BA.2 known as BA.2.12.1 and BA.2.12.2. These two subtype variants accounted for only 1.5% of new sequencing-positive cases until March 19, after which they began to spread rapidly. New York State public health officials warn that BA.2 is at least 30% more transmissible than BA.1, while BA.2.12.1 is thought to be 23%-27% more transmissible than BA.2.
During the week of April 16-23, BA.2.12.1 appeared to be more dominant of the two variants, with the proportion of cases caused by this variant increasing from 19.6% to 28.7% in the United States. According to data released by the US Centers for Disease Control and Prevention (CDC) on May 3, BA.2.12.1 has accounted for 36.5%. In the past two weeks, the increase has been close to 100%.
CDC Director Rochelle Valensky said additional evaluations are currently underway to understand the impact of BA.2.12.1 on vaccine effectiveness.
"BA.2 has 53 mutations, 29 of which are in the spike protein," said Dr. Angela Blanche, co-principal investigator in the Division of Vaccine Therapeutics and Evaluation at the University of Rochester Medical Center. Increased ability to transmit. The BA.2.12.1 subtype also has this enhanced ability to replicate and transmit from person to person...seems to be the dominant variant in the U.S. in the coming weeks."
BA.2.12.2 accounts for about one-third of all cases in the United States, according to CDC estimates. Currently, the cases of BA.2.12.2 are increasing exponentially. At that rate, expect to see a sharp increase in related cases nationwide in the next month or so.
BA.4 and BA.5 lead to surge in confirmed cases in South Africa
In addition to BA.2.12.1, two other mutant strains of Omicron, BA.4 and BA.5, have also raised concerns.
World Health Organization (WHO) Director-General Tedros Adhanom Ghebreyesus said at a press conference in Geneva on the 4th that two subtypes of the Omicron strain, BA.4 and BA.5, were responsible for the recent surge in cases in South Africa. Tedros said it was too early to determine whether the BA.4 and BA.5 subtypes caused more severe symptoms, but they were another proof that the new crown epidemic is not over.
WHO began tracking BA.4 and BA.5 in mid-April. BA.4 and BA.5 "have acquired a number of additional mutations that may affect their characteristics," WHO updated its weekly epidemiology report.
In addition to the seven provinces of South Africa, Australia, Austria, Belgium, Israel, Denmark, France, Germany, Both subtype variants have also been detected in more than 20 countries, including Pakistan, the United Kingdom, the United States and Switzerland.
Oliveira noted that BA.4 and BA.5 appear to be more infectious than BA.2, the two new variants "mutated in lineages that allow the virus to evade immunity." They are expected to spark a new wave of infections and possibly surpass the protective efficacy of some vaccines. Taking into account vaccinations and Covid-19 infections, it is estimated that more than 90% of the South African population has some degree of immunity.
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