The shortest 14-second transmission of Delta is why it is so menacing

  The 7 latest and most concerned virus issues are here!

  The recent new crown epidemics in various places are inseparable from the Delta mutant strain.

In the previous May and June, the new crown epidemic in Guangzhou was caused by the Delta mutant strain.

  However, do you really understand it?

  1. How wide is the global impact of Delta virus?

  The World Health Organization announced on July 28 that the Delta variant virus has spread to 132 countries and regions. The Delta strain has the most serious infections in the United Kingdom and India. Nearly 90% of the newly confirmed cases in these two countries are caused by Delta. Tower leads.

On May 21, 2021, a 75-year-old woman in Liwan District, Guangzhou City, Guangdong Province, China (who developed symptoms on May 18) was confirmed as a local case of new coronary pneumonia.

The detected cases have the same RNA sequence as the highly infectious delta variant (B.1.617.2) first discovered in India.

  2. How did Delta become the strongest mutant strain?

  At the WHO routine press conference for new coronary pneumonia held on April 16, 2021, Maria Van Kokhoff, the technical director of WHO's health emergency project, stated that the "double mutant" virus found in India carries E484Q and L452R mutations.

This characteristic makes Delta mutant strains have the characteristics of strong transmission, short incubation period, high viral load, rapid disease development, high proportion of severe illness, and possible immune escape phenomenon.

The US "Nature" magazine quoted a study from China on July 27 that "the concentration of virus particles in a person infected with Delta virus is about 1,000 times that of the original strain of the new crown virus."

  3. What are the symptoms after being infected with Delta?

  The atypical symptoms became the first impression of the delta strain of the medical staff.

On the evening of July 27th, Qiu Haibo, an expert from the Jiangsu Working Group of the Joint Prevention and Control Mechanism of the State Council, the vice president of Southeast University, and an expert in critical care medicine, introduced that, unlike the original fever and no nasal discharge, the delta strain in Nanjing After infection, the early symptoms may simply be fatigue, or dysosmia, or mild muscle soreness.

So it means that its symptoms are very atypical.

  4. Has the delta transmission method changed?

  Feng Zijian, a researcher at the Chinese Center for Disease Control and Prevention, stated at a press conference on epidemic prevention and control and new crown virus vaccination held by the State Council’s Joint Prevention and Control Mechanism on July 31 that the mode of transmission of the delta strain has not changed, and it is still flying through the respiratory tract. Foam transmission, contact with pollutants, air transmission or aerosol transmission.

According to a report from the Beijing News on June 21, the Guangzhou police discovered in the process of contacting and tracing a four-generation key case that Huang and Lu (the fourth-generation infected person) entered the bathroom separately while having a meal. The spread of the virus was completed in 14 seconds without touching the limbs.

A tracked case in Australia showed that the driver of the Delta new coronavirus variant strain caused the infection when three patients passed by the road, shopping mall or cafe, but each time the distance was 10 to 60 cm and the connection time was only a few seconds. .

  5. What kind of environment does Delta like best?

  The confined indoor environment is the main scene of virus transmission.

The morning tea transmission chain of the Guangzhou epidemic, the Yangzhou Mahjong Hall transmission chain of the current round of the epidemic, the transmission chain of Jingzhou Railway Station, and the transmission chain of the cruise ship crossing the Zihe in Changde all have this characteristic.

Academician Zhong Nanshan emphatically reminded him in his speech on "The Current Status and Judgment of the New Crown Epidemic" in Guangzhou that because the delta strain has a high viral load and the exhaled gas is highly toxic, you must wear a mask in places with a large number of people and poor ventilation.

  6. Will Delta mutate again?

  According to a report on the "India Today" TV website in June, the "Delta" variant further mutated to derive the "Delta +" (Delta +) or "AY.1" variant.

The "Delta Plus" variant is similar to the original "Delta" strain. It is formed by the mutation of the spike protein in the "Delta" variant. This new mutation is named "K417N", which helps the virus enter and Infect human cells.

  The US Consumer News and Business Channel (CNBC) reported on June 24 that the "Delta Plus" variant has three worrying characteristics: increased infectivity, stronger binding to lung cell receptors, and possible reduction in cell weight. Cloning antibody response.

"Because of the large number of infected people, giving the new coronavirus more opportunities to mutate and be selected, new mutant strains will continue to appear..." On the afternoon of August 4, Director of the Research Center for New Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Researcher Shi Zhengli, deputy director of the Wuhan (National) Biosafety Laboratory, told reporters.

  7. Does the new crown vaccine have an effect on the Delta strain?

  A paper published online on June 12 in the "Chinese Center for Disease Control and Prevention Weekly (English)" analyzed the impact of vaccination on cases infected with the "Delta" strain.

The paper disclosed that compared with unvaccinated cases, vaccinated cases showed three characteristics: short time from diagnosis to antibody positive, high CT value, and short hospital stay.

Are domestic vaccines useful for delta variants?

Academician Zhong Nanshan introduced that based on the study of the outbreak of the delta variant of Guangzhou's new crown virus in May this year, the results proved that the domestic vaccine is protective.

(According to Health Times)

  Delta is more infectious and the symptoms are hidden

  The Centers for Disease Control and Prevention (CDC) published a new study on Delta virus on its official website, one of which involves delta virus excretion data.

The data shows that Delta's virus shedding period reached 18 days, which is 5 days longer than the new coronavirus shedding period in the past 13 days.

  Wachter, head of the Department of Medicine at the University of California, San Francisco, said that Delta not only has a stronger transmission power, but also has a longer contagion period (18 days instead of 13 days), which will also challenge the 14-day quarantine measures we usually use.

  At the same time, according to the internal disclosure documents of the US CDC, the transmission capacity of the Delta mutant strain is comparable to that of the highly transmitted infectious disease chickenpox.

  At present, the infectivity of the delta mutant strain has surpassed SARS, Ebola, Spanish flu and smallpox virus, reaching an infectivity level similar to chickenpox. The infected person can infect 5 to 9 people.

And it is more likely to cause severe illness.

However, the infectivity of the original new coronavirus strain in the early stage is close to that of the common cold, and its infected person may infect 2 to 3 people.

  The delta strain was first discovered in India in October 2020. This mutant strain was named B.1.617 by the WHO and was named with the Greek letter δ (delta) on May 31 this year. It was discovered, but now only 10 months.

  Against Delta

  Many institutions are already developing new vaccines

  On August 5, according to a report from China Business News, Yin Weidong, chairman of Kexing Holding Biotechnology Co., Ltd., said in an interview that Kexing will submit to the drug regulatory authorities of various countries in the near future the Gamma strains of Kerlaifu and Delta strains. The clinical research and emergency use application of Kerlaifu.

In addition, China Biosciences is advancing the research and development of inactivated vaccines against multiple mutant strains.

It is reported that Zhongsheng is currently in the process of developing an inactivated vaccine against beta variants and is currently in the stage of animal experiments.

Inactivated vaccines against delta variants are also under development.

  Tao Lina, the former chief physician of the Shanghai Centers for Disease Control and Prevention's Immunization Program, said in an interview that the current more effective methods include: First, design vaccines specifically for variant strains.

Second, boost with existing vaccines to increase antibody concentration and resist mutant strains.

Third, find the relatively stable part of the virus that is not easy to mutate, and design a broad-spectrum vaccine.

  At the press conference of the Joint Prevention and Control Mechanism of the State Council on August 5, He Qinghua, the first-level inspector of the CDC of the National Health Commission, said that relevant scientific research and epidemic prevention and control practices at home and abroad have shown that the Delta mutant strain did not cause the new crown. The biological characteristics of the virus have undergone subversive changes, the source of infection and the route of transmission are basically clear, and the existing epidemic prevention and control measures are still effective for the delta mutant.

  Wang Liming, a professor and doctoral supervisor at the Institute of Life Sciences of Zhejiang University, recently wrote that six vaccines have been approved for use in China (Kexing, Sinopharm Beijing, Sinopharm Wuhan, Kangtai, Kangsino, Zhifei), covering inactivation Vaccines, adenovirus vector vaccines, recombinant protein vaccines and other routes.

There are also several vaccines in the development process.

As of August 5, 2021, the domestic vaccination dose has exceeded 1.7 billion doses, ranking first in the world.

With the emergence of more virus mutations in the future, the protective effect of domestic vaccines may be affected.

Wang Liming also pointed out in the article, “In the future where the new crown virus and humans coexist for a long time, regular injections of the new crown vaccine every year to strengthen the immune effect and deal with new mutant strains that appear from time to time may become part of our lifestyle."

  Chengdu Commercial Daily-Red Star News reporter Wu Yang