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Can China achieve COVID-19 herd immunity when vaccines 70% effective?
Can China achieve COVID-19 herd immunity when vaccines 70% effective? So is China’s vaccine useful?
On the morning of August 20th, Zhong Nanshan, academician of the Chinese Academy of Engineering, delivered a video speech at the 5th China-Arab States Expo Big Health Industry Forum and the 3rd “Internet + Medical Health” Application Conference. The latest research and judgments have been made on topics that are currently attracting wide attention, such as Tatovirus strains.
Zhong Nanshan said that research on the previous Guangzhou epidemic showed that the overall protection rate of the Chinese inactivated vaccine against the Delta strain was close to 60%, and the critical illness protection rate was 100%. The latest data show that the antibody level increased by more than 10 times when the second dose of domestically-made inactivated vaccine was vaccinated 6 months later. After more than 80% of the population is vaccinated, China can establish effective herd immunity.
Currently, 9 vaccines in mainland China have been conditionally marketed or used urgently.
“So is China’s vaccine useful?”
Zhong Nanshan listed several recent research results. The first is about the actual application of the Chinese Coxing vaccine in Chile, which was published in the New England Journal of Medicine in July this year by personnel from the Chilean Ministry of Health.
The data shows that through the study of more than 10 million people over the age of 16 vaccinated with Kexing vaccine, the effective rate of Kexing vaccine to prevent new coronavirus infection is 65.9%, the effective rate of preventing hospitalization is 87.5%, and the effective rate of preventing severe illness is 90%. , The prevention of death is 86%. Zhong Nanshan said that this shows that Kexing vaccine has a good preventive effect on the new coronavirus.
Another study, published in The Lancet, showed that the effective rate of Kexing vaccine in Turkey was 83.5%, and there were no reports of serious adverse reactions and deaths due to vaccination. Zhong Nanshan introduced that this study also shows that Kexing vaccine has a good protective effect on vaccinators, and is safe and tolerable.
Regarding the current concern about Delta strains, Zhong Nanshan said that current laboratory studies have shown that Chinese vaccines such as Kexing have a reduced protective effect on Delta strains, but they are still “very effective.”
In the recent Guangzhou epidemic, a total of 153 people were infected with the Delta strain. Zhong Nanshan introduced that by comparing patients with Chinese vaccines and non-vaccinated patients, it was found that Chinese inactivated vaccines have a protective effect on Delta strains. The overall protection rate is close to 60%, and the protection rate for moderate symptoms is 70%. The protection rate reached 100%. This research has just been published in the journal Emerging Microbes Infections in recent days.
How long will the immune function decline after vaccination?
Zhong Nanshan listed relevant information about Israel and the United States respectively. Israel is the country with the highest vaccination rate in the world, and the number of cases has dropped sharply. At the beginning of vaccination, the protection rate of Pfizer vaccine used in Israel reached 95%, but after half a year, the protection rate dropped to 39%. Zhong Nanshan pointed out that this shows that the effective rate of the mRNA vaccine can be maintained for half a year.
The number of confirmed cases in the United States also rebounded in August. Zhong Nanshan believes that it can be estimated that the protection rate of vaccines usually declines after half a year of vaccination.
“Inactivated vaccines or mRNA vaccines, half a year after vaccination, the immune function has been significantly reduced. Various countries are discussing how to strengthen the immune effect of vaccines. Countries that vaccinated inactivated vaccines and mRNA vaccines have tested 6 after two doses. One more dose every month will have the effect.” Zhong Nanshan said.
According to the latest Chinese research data, if another dose is given 6 months after the second dose of vaccine, the antibody level has increased significantly by more than 10 times, and it will remain at a relatively high level 6 months after vaccination.
“It looks like this is a very promising method of boosting immunity.” Zhong Nanshan said that at present, the data on the level of boosted immunity after the mRNA vaccination abroad has not yet been counted, and the protective effect of Chinese booster vaccination in the real world has yet to be further proved.
What level of vaccination does China need to achieve to achieve “herd immunity”?
Zhong Nanshan said that this is related to the effectiveness of the vaccine and also depends on the spread of the virus. “The effective rate of vaccines in China is about 70%, so China needs more than 80% of the entire population to be vaccinated to establish an effective herd immunity. Now, China’s vaccination rate may reach more than 80% by the end of this year. “
(source:internet, reference only)