Our reporter Ye Qing
Ask about the new crown vaccine
Are domestic vaccines useful for Delta variants?
"Effective and very safe." On July 31, Zhong Nanshan, an academician of the Chinese Academy of Engineering, replied clearly when attending a summit event 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.
The delta variant has become the main variant of the global spread of new coronary pneumonia.
On July 27, Nanjing notified that the mutant strain that caused the Nanjing epidemic was the Delta mutant.
"When we encountered the delta mutant strain for the first time in Guangzhou, we still adopted the method of the past at first, but it did not work. We found that the speed of isolation of new patients was far behind the speed of the virus. I was also very much in my heart at the time. Anxious." Zhong Nanshan recalled.
Why does the delta variant spread so quickly?
"The viral load of the delta mutant strain in the human body is 100 times higher than that of the ordinary strain, and its transmission power is stronger; the incubation period in the body is shorter, and it only takes 1-3 days to become onset; it also takes a longer time to turn negative in the body. It lasts for 13-15 days, which is much longer than the 7-9 days for ordinary strains." Zhong Nanshan pointed out that because of the high viral load in the infected person's body, the infectivity has increased.
For example, the Guangzhou epidemic has 5 generations of transmission within 10 days.
The spread of the Nanjing epidemic once again confirmed the speed of the Delta mutant strain.
"The Nanjing epidemic is similar to that of the virus that caused the Guangzhou '5.21' epidemic in terms of load, infectivity, and concealment. Most patients are mildly ill." Zhong Nanshan pointed out that the Nanjing Municipal Government has taken timely preventive and control measures. It is believed that the Nanjing epidemic is controllable as a whole."
Most of the earliest infected persons in this round of the epidemic in Nanjing have been vaccinated.
Does the current domestic vaccine have a protective effect on the delta mutant?
Should the vaccine be used or not?
"Effective and very safe." Zhong Nanshan said firmly, using a set of verified scientific data to illustrate.
From the clinical immunization results, in response to the new coronavirus variant, the positive conversion rate of the immune serum vaccinated with the Kexingxin crown inactivated vaccine against the delta variant strain decreased slightly, reaching 87.5%; while the Sinopharm vaccine against the Alpha strain, Both Beta strain and Delta strain have protective ability. The neutralizing ability of Alpha strain is reduced by 6.7%, and the protective ability is basically unchanged; the neutralizing ability of Beta strain and Delta strain is reduced by 47% and 32%, respectively.
"The laboratory inspections of these Chinese vaccines found that their comprehensive strength in killing the virus has decreased, but they still have a protective effect." Zhong Nanshan said.
According to him, 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.
Preliminary statistics of the study show that the protective effect of the vaccine on severe cases is 100%, and the protective effects on moderate, mild, and asymptomatic are 76.9%, 67.2%, and 63.2%, respectively.
Related research results will be published later.
“Of the 13 severely ill patients that appeared in the Guangzhou epidemic, 4 received ECMO (Extracorporeal Membrane Oxygenation, commonly known as “artificial lung”). We were all rescued. None of them were vaccinated.” Zhong Nanshan added.
In the face of the still severe global epidemic prevention and control situation, what do we need to do?
"Can't relax, we must always pay attention to community prevention and control measures to establish herd immunity." Zhong Nanshan emphasized that in densely populated places with poor ventilation, we must wear masks.
In Zhong Nanshan's view, natural immunity is unrealistic, unscientific, and inhumane.
"Mass vaccination to achieve herd immunity requires two to three years of global collaboration. At present, my country has the largest number of vaccinations, but due to the large population base, the proportion of vaccinations per 100 people in China is not high. In China, A vaccination rate of 83.3% is needed to achieve herd immunity." Zhong Nanshan believes that vaccination should be accelerated next and the development of more effective vaccines against delta variant infections should be accelerated.