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Recently, the epidemic situation in Jiangsu, Henan, Hunan, Beijing, Shandong and other places has been sporadic, and sporadic confirmed cases have continued to appear. Friends who pay attention to the development of the epidemic have heard a word frequently during this time - Delta strain.
On July 27, Ding Jie, deputy director of the Nanjing Municipal Center for Disease Control and Prevention, informed that the strain of the Nanjing epidemic was the new coronavirus variant delta; on August 1, Zhao Dongyang, deputy director of the Henan Provincial Center for Disease Control and Prevention, said that after virus sequencing and comparative analysis, the epidemic in Henan was mainly caused by the delta strain of the new crown virus.
Delta strain: Faster spread and highly contagious
First discovered in India in October 2020, Delta strain is the fastest-spreading and most powerful strain of COVID-19 ever discovered worldwide.
According to relevant research from Public Health England, the Delta strain has 100% more transmission capacity than the original strain; compared with the alpha strain that became popular around the world in the second half of last year, its transmission capacity is 60% higher!
Specifically, the terrible thing about delta strains is that:
1. The viral load of the Delta strain that can be infected in 14 seconds without contact is 1260 times that of the epidemic strain last year, which is extremely contagious, and even if there is no contact, it can be infected in 14 seconds.
The Guangzhou police, who are responsible for assisting in the epidemiological investigation, once released a surveillance video: in the same restaurant, Huang Mou (the third generation of infected persons) and Lu Mou (the fourth generation of infected people) successively went into the bathroom, and without any physical contact, the virus was transmitted in 14 seconds.
2. The basic number of infections (R0) of the original strain of the new crown is greatly improved compared to the original, which is greatly improved by the original, and the basic number of infections of the Delta strain is about 5-8. That is to say, in the past, one person could infect two or three people, and now one person can infect eight people, and the scope of transmission is wider.
3. The incubation period is shortened, and the onset of disease is faster in contact with the original strain, it takes an average of 6 days to detect the virus; and after 4 days of contact with the Delta strain, the virus can be detected in the infected person. The incubation period of the virus is about two days shorter than the original, and the onset of the disease is faster.
4. Increased toxicity. Academician Zhang Boli said that from the domestic data, the time for the sick population to turn yin is prolonging, and more people have turned from mild to severe disease.
5. Have immune escape ability. Data released by Public Health England shows that after a complete 2-dose Pfizer vaccine, the effectiveness against alpha strains reached 93.4%, while the protection against Delta strains was only 87.9%. This means that delta strains have a certain "immune escape" ability – that is, the ability to produce antibodies after vaccination and prevent infection.
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Source: Morning News Comprehensive Science China, CCTV News Client, CCTV Network, Guangming Daily