Zhong Nanshan gives the latest analysis on the epidemic issues you are concerned about

Are domestic vaccines effective against the Delta strain?

“It works and is very safe.”

On July 31, Zhong Nanshan, an academician of the Chinese Academy of Engineering, gave a clear answer at a summit in Guangzhou. He pointed out that my country needs an 83.3% vaccination rate to achieve herd immunity. For this reason, he especially called on everyone to pay attention to vaccination.

Photo provided by the unit where Academician Zhong Nanshan was interviewed

In just ten days, the Nanjing epidemic has spread to more than 20 cities in 15 provinces. On August 1, there were 55 new local cases in my country. In this round of epidemic, the "Charming Xiangxi" performance in Zhangjiajie, Hunan, and the "Chuan Zihe No. 3 Cruise" in Changde are becoming new cross-gathering locations for transmission.

"This shows that closed environments are an extremely important window for the spread of the new coronavirus. In closed spaces such as airplanes, trains, and subways, air cross-infection is prone to occur due to insufficient air purification." Zhong Nanshan pointed out that this deserves great attention.

Photo provided by the interviewed unit at the scene where Academician Zhong Nanshan gave a report

On July 27, Nanjing reported that the virus strain that caused the Nanjing epidemic was the Delta strain. The Delta strain has become the main variant of the COVID-19 virus in the world.

"When we first encountered the Delta strain in Guangzhou, we initially used the old methods, but they no longer worked. We found that the speed at which new patients had to be isolated was far slower than the speed of the virus. I was very anxious at the time," recalled Zhong Nanshan.

Why does the Delta strain spread so quickly? "The Delta variant has a 100-fold higher viral load in the human body than the common strain, making it more transmissible. It has a shorter incubation period in the body, with symptoms occurring in only 1-3 days. It also takes longer to turn negative in the body, up to 13-15 days, much longer than the 7-9 days of the common strain." Zhong Nanshan pointed out that it is precisely because the viral load in the infected person is high that the infectiousness is enhanced. For example, the Guangzhou epidemic had five generations of transmission within 10 days.

"The Nanjing epidemic is similar to the virus strain that caused the Guangzhou '5.21' epidemic in terms of virus load, infectiousness, and concealment, and most patients have mild symptoms. The epidemic broke out in a concentrated community near Nanjing Lukou International Airport, and the infected population is concentrated in their occupations. The Nanjing Municipal Government has taken timely prevention and control measures. I believe that the overall epidemic in Nanjing is controllable." Zhong Nanshan said.

Most of the earliest infected people in this round of epidemic in Nanjing have been vaccinated. So does the current domestic vaccine have any protective effect against the Delta strain? Should we get vaccinated or not? "It is effective and very safe," Zhong Nanshan said firmly, using a set of verified scientific data to illustrate his point.

According to him, based on the research on the outbreak of the Delta variant of the novel coronavirus in Guangzhou in May this year, the results showed that the domestic vaccine has a protective effect. Preliminary statistics from the study show that the vaccine has a 100% protective effect against severe cases, and a protective effect of 76.9%, 67.2%, and 63.2% against moderate, mild, and asymptomatic cases, respectively. Relevant research results will be published later.

In the face of the still severe global epidemic prevention and control, what do we need to do? "We cannot relax and must always pay attention to the prevention and control measures in the community and the establishment of herd immunity." Zhong Nanshan emphasized that masks must be worn in crowded places with poor ventilation.

In Zhong Nanshan's view, natural immunity is unrealistic, unscientific and inhumane. "Large-scale vaccination to achieve herd immunity requires 2 to 3 years of global collaboration. At present, my country has the largest number of vaccines, but due to the large population base, the proportion of vaccines per 100 people in China is not high. In China, an 83.3% vaccination rate is required to achieve herd immunity." Zhong Nanshan believes that vaccination should be accelerated in the future, as well as the development of vaccines that are more targeted to Delta variant infections.

Source: Science and Technology Daily, Reporter: Ye Qing

Editors of this issue: Hu Hongjiang, Shi Lei