Chinanews client, Beijing, July 31 (Zhang Yilin) ​​The Nanjing epidemic continues to be focused by public opinion. From the 20th to the 30th, there have been 190 confirmed cases in Nanjing, and the epidemic has affected many provinces and cities.

  Since the beginning of this year, sporadic epidemics have appeared in many places, and a term has continuously entered the public eye-"Delta strain".

From the Guangzhou epidemic to the Ruili epidemic, and then to the Nanjing epidemic, the "delta" of the country has been constantly knocked on, how to prevent it?

On July 29, Nanjing carried out the third round of nucleic acid tests for all permanent residents and foreigners in the city.

Photo by Yang Bo

Delta is making waves all over the world

  On July 30, at the press conference on the epidemic in Nanjing, Ding Jie, deputy director of the Nanjing Centers for Disease Control and Prevention, introduced that the current round of the epidemic in Nanjing was in the same transmission chain, and the source of the epidemic was the inbound flight of Russia CA910 on July 10.

In addition, Nanjing has completed the sequencing of the virus genes in 52 related cases, all of which are Delta strains. The virus genome sequence is highly homologous, suggesting the same transmission chain.

  Because of the Nanjing epidemic, the term "delta strain", a term that often appears in international news, has begun to become a topic of discussion among the domestic people.

  The delta strain was first discovered in India in October last year. The WHO named it B.1.617 and named it with the Greek letter δ (delta) on May 31 this year.

  This strain has new characteristics such as strong virus transmission, better adaptation to the human body, fast replication, high body load, slow conversion of patients, long treatment time, and prone to severe illness.

  According to the World Health Organization, "Delta strain is the most powerful new coronavirus mutation discovered so far."

The WHO introduced on the 28th that at present, the delta variant virus has spread to 132 countries and regions.

On July 28, at a nucleic acid testing spot on the streets of Nanjing, medical staff conducted nucleic acid testing and sampling for citizens in the dark.

Photo by China News Agency reporter Yang Bo

How "poisonous" is Delta?

  In fact, the Nanjing epidemic is not the first time that my country has confronted Delta head-on.

Since the beginning of this year, Guangdong, Yunnan and other places have seen new crown epidemics caused by the delta strain.

  For example, from May to July this year, the delta mutant strain caused epidemics in Guangzhou, Shenzhen, Dongguan and other places.

  In Ruili, Yunnan, the sequencing results of 7 positive samples of the new coronavirus tested in July this year also showed that the genome sequence is highly homologous to the Delta mutant.

  How "poisonous" is Delta?

Feng Zijian, a researcher at the Chinese Center for Disease Control and Prevention, once said that from the Guangzhou epidemic, the infectivity and transmission ability of the delta virus variant strain has been significantly enhanced, and the incubation period or generation interval has been shortened, and it has been transmitted for five or six generations in just 10 days.

  In June of this year, Zhong Nanshan, an academician of the Chinese Academy of Engineering, described it vividly: "As long as the patient is in the same space, unit, and building 4 days before the onset of illness, they are considered close contacts."

  The spread of Delta is also supported by international data.

According to statistics from the US Centers for Disease Control and Prevention, in May this year, only 1% of the new cases in the United States were infected with the Delta strain. Now, the Delta strain infection accounts for about 83% of the newly confirmed cases.

  According to the global epidemic analysis released by the World Health Organization on the 20th of this month, it is expected that Delta will become a major global epidemic strain in the next few months.

Data map: The staff is doing sample testing.

Photo by Wang Qian

It has a "very atypical" feature

  According to Zhong Nanshan's analysis, the Delta strain has a high viral load. Once the human body is infected with the Delta strain, the viral load in the body is higher than the previous ordinary strain.

The incubation period is short, and the incubation period of the virus in the human body is about 1 to 3 days, and some even get sick within 24 hours.

  In addition, the nucleic acid turns negative for a long time, and the patient is infected with a common virus strain. The nucleic acid test turns negative after 7 to 9 days after treatment. However, among the more than 100 patients in Guangdong before, the average time to turn negative was 13 to 15 days, which is almost high. Doubled.

  In addition to the virus itself, patients with the delta strain have another important feature: the symptoms are extremely atypical.

  "After the delta strain infection in Nanjing, the early symptoms may only be fatigue, or dysosmia, or mild muscle soreness. Therefore, its symptoms are very atypical." The State Council Joint Prevention and Control Mechanism Comprehensive Group Jiangsu Work Introduction by Qiu Haibo, an expert in the medical treatment team, vice president of Southeast University, and an expert in critical care medicine.

  Based on this characteristic, Qiu Haibo specially reminded that it is precisely because of the extremely atypical symptoms that people should pay attention to their health in time while wearing masks, washing hands frequently, and gathering less.

On July 26, the Nanjing "Fire Eye" laboratory was stepping up its construction at the Nanjing International Expo Center, with staff debugging equipment.

Photo by China News Agency reporter Yang Bo

Will the vaccine still work against Delta?

  After the outbreak in Nanjing, Yang Yi, director of the Department of Critical Care Medicine, Zhongda Hospital of Southeast University, revealed in an interview with the media on the 22nd of this month that most of the confirmed cases in this round of the epidemic in Nanjing had been vaccinated.

  So, is the vaccine we vaccinated against the mutant virus?

  According to experts, the answer to this question is still clear: the vaccine is still effective, and vaccination is urgent.

  Regarding the Nanjing epidemic, Yang Yi said that the overall symptoms of the vaccinated cases were relatively mild, the probability of turning into a severe case was significantly lower, and the course of the disease was relatively short.

It shows that vaccination still has a protective effect.

  Zhong Nanshan also stated in June that common domestic vaccines are effective against delta mutant strains, and that everyone should speed up the pace of "receiving everything."

He mentioned that in the spread of the delta strain, the main and severely ill patients are mostly elderly people, but also children. These two groups of people should be vaccinated.

  On July 29th, Yang Xiaoming, chairman of Sinopharm Group China Biotech, told the media that through the laboratory, the serum of the immune population formed after inoculation of the China Biotech New Coronary Inactivated Vaccine will be crossed with multiple new coronavirus variants sweeping the world. And experiments, it was found that China's biological new crown inactivated vaccine can achieve cross-neutralization against four typical variant strains, including the Delta strain. In other words, the China's new biological new crown inactivated vaccine can still provide effective protection.

  Yang Guang, Chief Commercial Officer of Kexing Biotech, also stated that Kexing Biotech has also conducted neutralizing antibody experiments on the sera of Kexing vaccinators with different variants, and has seen significant effects.