Will more than 90% of new crown vaccinations end the outbreak?

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The latest data communicated by the National Health Commission on October 24 shows that there are 3784 confirmed cases of new crown pneumonia (including 15 severe cases).

Previously the social surface clearance areas, there are also sporadic distribution of cases. For example, Beijing has seen infected people found by social surface screening for several days in a row, and there is still a potential for an aggregated outbreak to occur.

The number of people vaccinated with the new crown vaccine in China has exceeded 1.3 billion, with a vaccination rate of over 90%. Many netizens believe that it is time to liberalize based on the current vaccination rate. Is this view correct, and can an epidemic be ended with a vaccination rate of more than 90% of the new crown vaccine? Science and Technology Daily reporter interviewed relevant experts.

Reporter: The current vaccination rate has reached more than 90%, the immune barrier has not yet been established?

Academician Gao Fu of the Chinese Academy of Sciences: The immune barrier established by vaccines provides 4 levels of protection against infection, morbidity, transmission, serious illness and death. The global data show that the effect of prevention of serious illness and death is very good, and the immune barrier of this level of protection has basically been established.

However, due to the mutable nature of viruses, the immune barrier against infection, morbidity and transmission still needs to be strengthened.

Zhu Tao, Chief Scientific Officer of Kangxinuo Bio: Several international and domestic studies have shown that no matter which technical route of the new crown vaccine is administered, the neutralizing antibodies in the body will improve quickly, but also decay faster. For example, the clinical data of foreign mRNA vaccine shows that the level of neutralizing antibodies in human body becomes low after 6 months after the 3rd dose. Therefore, some countries have blocked the spread of the epidemic through continuous booster shots, such as Israel and other countries have carried out the 4th and 5th doses of the original strain of vaccine, but this is not a long-term solution.

Reporter: What is the key to interrupting the epidemic?

Academician Gao Fu of the Chinese Academy of Sciences: To stop the epidemic, an immune barrier is needed, but after the immune barrier is established, there is a breakthrough infection, and the game between human and virus is like a “cat and mouse game”, always in competition. At present, we call on people not to have “vaccine hesitation”, and should receive the booster vaccination as soon as possible, and whether the fourth vaccination will be given and what kind of fourth vaccination will be given, the country will make further judgment according to the epidemic situation and risk-benefit ratio.

Zhu Tao, Chief Scientific Officer of Kangxinuo Bio: In order to stop the epidemic, the role of the vaccine should not only be to reduce the incidence rate, but also to sufficiently reduce the infection rate in order to really control the epidemic.

If the epidemic is always unstoppable and there is always infection and transmission of new coronavirus in the population, it means that it has the chance to keep mutating and producing new mutant strains, forming a cycle of infection-mutation-epidemic development-re-infection.

Reporter: Immunity still needs to be strengthened again, what kind of effect should be achieved?

Hu Zhenxiang, head of research and development of Lizumab: Re-boosting cannot be a “fix” on the basis of the original vaccine, but a new vaccine strategy. The sequential boosting of vaccines of different technical lines is crucial to induce higher neutralizing antibodies than homologous boosting. The study of Likang V01 vaccine, the only one in China that has completed a large phase III clinical study with Omicron variant, showed that by arming the vaccine with “three heads and six arms” to stimulate helper antibodies and T-cell responses, the absolute protection rate against the new coronavirus (including Omicron variant) could reach 61.35%. The vaccination is now available in Anhui and Guangdong.

Zhu Tao, Chief Scientific Officer of Kangxinuo Bio: Stimulating mucosal immunity is recommended by the World Health Organization for use with half the effort. It allows the body’s mucosal surface to produce IgA and cellular immunity to capture and clear the new coronavirus when it first enters, which has a more positive effect on interrupting transmission.

The Concierto inhalation vaccine is the world’s first approved inhaled neo-coronavirus vaccine, and training and preparation for vaccination is currently being done. There are also more than a dozen clinical products of nasal spray and inhalation vaccines under development in countries around the world, and it is becoming a consensus to stimulate mucosal immunity to block virus transmission earlier.

Reporter: What kind of immune barrier can completely end the outbreak?

Tao Zhu, Chief Scientific Officer of Concepino Biologicals: Don’t expect to be immunized once and for all. I think it takes a long time to build up an immune barrier, and there are different strains of viruses, and we have different generations of vaccines to fight against them. Weakness of the virus.

Reporter: Isn’t it one of the prerequisites for liberalization that the vaccine is reinforced again?

Hu Zhenxiang, head of research and development of Lizumab: I think it can be said that before the liberalization, another sequential booster immunization against Omicron should be carried out, especially for the most at-risk groups after the liberalization: one group of people with underlying diseases and the elderly, these groups usually have a high proportion of moderate and severe diseases after infection, and if they have a serious illness, it may cause a shortage of medical resources. The second category is for special industry populations, such as hospitals, customs and other key populations with high exposure risk, which also need further protection.