In response to the online news that “China plans to launch covid-19 vaccine to strengthen the mixed vaccination scheme and Chongqing Zhifei Biological Products Co.Ltd(300122) and Cansino Biologics Inc(688185) are selected”, the reporter of science and Innovation Board daily learned from people close to the disease control system that there is no doubt about the safety of mixed vaccination in disease control, but the specific vaccination scheme is still under study and has not yet formed an official document.
“The most important thing is the consideration at the policy level, such as the establishment of vaccination awareness, vaccination methods, which vaccine to choose as the reinforcing needle of ‘mixed vaccination’, etc.” Chongqing Zhifei Biological Products Co.Ltd(300122) replied to reporters that the company had not received the relevant notice.
previously reported
China will launch sequential vaccination of covid-19 vaccine, and the booster needle can be heterologously vaccinated with non inactivated vaccine
“Strengthening the vaccination of homologous or heterologous vaccines can improve the level of neutralizing antibodies, but the effect of heterologous vaccination will be better. Today, relevant national departments have trained the disease control vaccination system and will start heterologous vaccination in the target population, that is, sequential vaccination.” A grass-roots vaccination personnel said.
First finance learned from relevant people that the state has put forward new relevant requirements for covid-19 virus vaccination in the future, and covid-19 virus vaccination continues to promote basic immunization and enhanced immunization. There are two kinds of booster immunization programs: one is homologous booster immunization, and the other is heterologous booster immunization (also known as “sequential booster immunization”).
The so-called homologous booster immunization means that booster immunization adopts the same technical route as basic immunization for vaccination. At present, China implements inactivated + inactivated vaccine booster or adenovirus vector + adenovirus vector vaccine.
The so-called sequential booster immunization refers to vaccination with vaccines different from the previous vaccine technology. At the present stage, China can implement inactivated + recombinant protein vaccine or inactivated + adenovirus vector vaccine.
Existing data show that homologous enhanced immunization and sequential enhanced vaccination combinations such as inactivated vaccine recombinant protein vaccine and inactivated vaccine adenovirus vector vaccine can greatly improve the neutralizing antibody level of recipients and have good safety.
An epidemiologist believes that at present, there are very few people with natural infection in China, and about 1 / 4 to half of the people abroad, both developed and developing countries, have experienced natural infection, which can produce higher immune protection than that induced by vaccines (including mRNA vaccines). There is also a certain proportion of people who have higher dual protection from natural infection and vaccination. Therefore, it is necessary for China to promote the sequential immunization of vaccines with different technical routes, and optimize the combination and efficacy of existing vaccines through heterologous sequential immunization strategy.
Omicron, which has a strong ability to break through immunity, is rapidly leading a new wave of epidemic in the world.
Due to the great mutation of the newly emerged Omicron variant in the S gene of the main target of the vaccine, resulting in the significant decline of neutralizing antibody titer and serious immune escape, how to improve the protective ability of the existing vaccine and whether to consider the upgrading of covid-19 vaccine have become the key problems at present.
In fact, it is not easy to update the vaccine immediately. Although relevant studies are advancing, the research data are not very optimistic. The monkey test results recently published by the research team of the National Institutes of Health (NIH) on the online journal platform biorxiv show that the new generation covid-19 vaccine mrna-1273.529 (also known as mRNA Omicron) of Omicron antigen being developed by Moderna company is used as the reinforcing needle, which is compared with the original covid-19 vaccine mrna-1273 developed by the company, There was no significant difference in protection.
How to further improve the ability to fight Omicron based on the existing covid-19 vaccine?
Sequential vaccination was proposed 10 years ago and has been proved to be effective in the research of influenza and other emerging virus vaccines. The sequential vaccination of covid-19 vaccine has also been confirmed by the scientific community.
A few days ago, the research team led by Professor Zhang Wenhong published an article on the research results of sequential vaccination on Omicron in newborn microorganisms and infection. Based on the two doses of inactivated vaccine, the researchers conducted the third dose of homologous enhancement and heterologous enhancement (sequential vaccination). The results showed that after the third dose of inactivated vaccine was enhanced for 14 days, the neutralizing antibody titers of vaccine original strain, delta strain and Omicron strain in serum increased to 285.6, 250.8 and 48.73 respectively If the third heterologous injection of recombinant subunit protein vaccine was used for 14 days, the neutralizing antibody titers of the original strain, delta strain and Omicron strain in serum increased to 1436, 1501 and 95.86 respectively.
These data suggest that both homologous enhancement and heterologous enhancement are effective for mutant strains, and the effect of heterologous enhancement is better.
As early as August 8, 2021, relevant researchers of the State Food and Drug Administration published the results of such research, “strengthening immunity with heterologous vaccine and effectively improving the protective immune response of inactivated covid-19 vaccine”. It can be seen that heterologous vaccination can further improve the protection of human body.
As of February 15, 2022, the total number of vaccinations in China was 1.267 billion, of which 1.231 billion had been vaccinated in the whole process; There are 502 million people who have been vaccinated, accounting for 35.6% of the total population. Compared with 55.3% in the UK, there is still a certain distance to go. Especially for people over 60 years old, the vaccination rate in China is low. The vaccination rate in 12 provinces is ≤ 80%. At present, less than 30% of people over 60 years old have been immunized. (source: First Finance)
