[Global Times reporter Zhao Juejuan Bai Yunyi Hu Yuwei] China's new crown vaccine sequential booster immunization (commonly known as "mixed fight") has been officially launched.
Wu Liangyou, deputy director of the National Health Commission's Bureau of Disease Control and Prevention, revealed on the 19th that with the approval of the State Council's joint prevention and control mechanism, the National Health Commission began to deploy sequential booster immunizations.
Previously, my country's new crown vaccine booster immunization was all homologous vaccination, that is, the first two shots were inactivated vaccines, and the third shot was also inactivated vaccine; the first shot was adenovirus vector vaccine, and the second booster shot was also adenovirus. Vector vaccine.
The booster sequential vaccination launched this time is also called heterologous vaccination, that is, the new crown vaccine using different technical routes for basic immunization and booster immunization.
There are two kinds of sequential strengthening combinations approved this time, namely "inactivated + recombinant protein" and "inactivated + adenovirus vector".
The inactivated vaccines used as basic immunity include the new crown vaccines produced by Sinopharm Zhongsheng Beijing, Sinopharm Sinopharm Wuhan and Beijing Kexing, excluding the two approved emergency use vaccines developed by the Institute of Medical Biology, Chinese Academy of Medical Sciences and Kangtai Biology for the time being. Inactivated vaccine.
There are two vaccines that can be used as sequential boosters, namely the recombinant protein vaccine of Zhifeilong Kema and the adenovirus vector vaccine of CanSino Bio.
In the past period of time, the homologous booster immunization that has been carried out in my country has shown a certain effect on preventing new crown infection and re-transmission, and has a significant effect on preventing pneumonia and severe disease.
The study found that within 6 months of completing immunization, the risk of pneumonia (common type and above) in patients with new coronavirus infection can be reduced by 60%.
In the close contact population, the breakthrough infection rates of basic immunization and booster immunization were 22.6% and 6.0%, respectively.
Boosting immunity can reduce Omikron's breakthrough infection rate by more than 3 times compared to basic immunity.
Zhuang Shili, a doctor who has been concerned about the new crown vaccine for a long time, told the "Global Times" reporter that after the new crown vaccine is vaccinated, the human body fights virus infection through antibody and T cell responses, and high levels of neutralizing antibodies are important to protect the human body from virus infection. Base.
However, the level of neutralizing antibodies will decline over time, and it will drop significantly when encountering variants with strong immune escape capabilities such as Omicron, which cannot play the original preventive effect.
Compared with two doses of inactivated vaccine plus one dose of inactivated homologous booster, heterologous booster is considered to have a better effect, and it is also a further supplement and improvement to the booster immunization strategy of the new crown vaccine.
Gao Fu, director of the Chinese Center for Disease Control and Prevention, said, "From the basic theory of immunology, vaccination should be 'small and multiple, heterogeneous vaccination'. 'Small and multiple' is in line with the basic principles of immunology. And 'heterologous vaccination', Theoretically speaking, using vaccine A as the primary immunization and boosting vaccination with B vaccine is better than the 'AA' and 'BB' vaccination programs." Zhu Fengcai, a well-known clinical vaccinologist and deputy director of the Jiangsu Provincial Center for Disease Control and Prevention, accepted the Global Times. The reporter also mentioned in the interview that, compared with the priming-boosting strategy of the same type of vaccine, sequential vaccination of different types of vaccines can improve the breadth, strength, durability and functionality of the immune response.
Shao Yiming, a member of the expert group for vaccine research and development of the joint prevention and control mechanism scientific research team of the State Council, said that for some viruses with strong variability, sequential immunization is often used.
The advantages of sequential immunization have two aspects: first, different vaccines can complement each other; second, different people have different physiques, and there may be more side effects for a certain vaccine, which is not suitable for multiple vaccinations. Vaccines can avoid side effects.
Shao Yiming emphasized that the vaccines approved for sequential vaccines have proven their safety in large-scale use, and some clinical studies carried out in China have not found more side effects of heterologous immunization.
Globally, countries including Turkey, Chile and other countries have approved the sequential vaccination of the new crown vaccine.
Chen Xi, an associate professor at the Yale School of Public Health, said that the effect of sequential strengthening of vaccines in reducing hospitalization and severe illness rates and reducing the burden on the medical system is obvious to all, and it is necessary for China's "dynamic zero" policy.