CanSino: COVID-19 Booster shot increases neutralizing antibodies about 8 times

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CanSino: COVID-19 Booster shot (2nd dose) can increase neutralizing antibodies about 8 times

CanSino: COVID-19 Booster shot increases neutralizing antibodies about 8 times.  Cansino’s COVID-19 vaccine is ecombinant COVID-19 Vaccine（Adenovirus Type 5 Vector, only one dose needs against COVID-19. 

Chief Scientific Officer of CanSino Bio: the booster shot of CanSino COVID-19 vaccine: Convidecia (Ad5-nCoV)  can increase the level of neutralizing antibodies in the body by about 8 times. 

On August 5th, Dr. Tao Zhu, co-founder and chief scientific officer of CanSino Bio, conducted an academic exchange on the clinical evaluation and application effects of the recombinant new coronavirus vaccine (type 5 adenovirus vector) Convidecia.

1. Why do we need mucosal immunity to prevent the new coronavirus?

Recently, the relevant clinical test results of the inhaled COVID-19 vaccine Ad5-nCoV were published in the authoritative international academic journal “The Lancet · Infectious Diseases”. The test results show that the administration method of atomized inhalation can stimulate mucosal immune response. So, what is the significance of mucosal immunity for preventing the new coronavirus?

Zhu Tao said that the difference between the new coronavirus and previous SARS viruses is that the new coronavirus can efficiently use a protein (TMPRSS2) rich in the surface of the respiratory tract. For the Delta strain, this effect on the surface of the respiratory tract is even more obvious.

Studies have shown that once a vaccinated person is infected with the Delta strain, whether it is mild or asymptomatic, the viral load in the upper respiratory tract is not significantly different from that of the unvaccinated person.

This characteristic causes the delta to spread very fast. It is precisely because of this feature that it is necessary to block the virus or reduce the viral load in the respiratory tract from the vaccine mechanism.

This is the most basic idea for the development of inhaled vaccines, which can block the virus in the respiratory tract infection through mucosal immunity.

It is generally difficult to produce neutralizing antibodies in the blood through mucosal immunity. Ad5-nCoV atomized administration not only produces mucosal immunity, but also maintains its strong systemic immunity characteristics.

2. Ad5-nCoV is still effective in preventing Delta strain

The technical route of CanSino Bio’s COVID-19 vaccine is an adenovirus vector, and the vaccine has been conditionally marketed in China. Regarding the adenovirus vector’s response to virus variants, Zhu Tao introduced that according to the data of the Huang Weijin research group of the China Inspection Institute, except for the slight decline of the South African strain (Beta), the adenovirus vector vaccine neutralizes the true viruses of 9 different viruses The antibody titers are similar.

Among them, the level of neutralizing antibodies against the Delta strain remains basically unchanged, and the neutralizing effect against the Indian strain (Delta) pseudovirus is about 0.9-1.4 times lower than that of the British strain (D614G). The inactivated vaccine against the Indian strain (Delta) The neutralization effect is about 1.4-2.3 times lower than that of the British strain (D614G).

Zhu Tao mentioned that the latest clinical research data showed that the level of neutralizing antibody remained at a high level 6 months after the initial immunization with Convidecia; a booster dose of vaccination can increase the level of neutralizing antibody in the body by about 8 times. Judging from the results of the neutralizing antibody cross-experiment conducted so far, the current vaccine has a protective effect on the mutant strain. CanSino Bio is also currently developing a COVID-19 vaccine against the mutant strain.

3. Research shows that: sequential strengthening has significant advantages

Under the background of virus mutation, the need for intensive injections has become the focus of attention from the outside world. At the sharing meeting, Zhu Tao mentioned that according to the results of a sequential immunization data independently carried out by the China Inspection Institute, the booster vaccination of mice that have been vaccinated with two doses of inactivated vaccines will enhance the effect of adenovirus vector vaccines. most.

In addition, according to a clinical study on the sequential immunization of the COVID-19 vaccine initiated by Jiangsu CDC researchers, after inoculation with 2 doses of inactivated vaccine, the third dose is boosted with adenovirus vector COVID-19 vaccine, and the antibody level is several times that of the inactivated COVID-19 vaccine. difference.

(The above data comes from China Jiangsu CDC researchers)

Talking about the strategies to deal with the current mutant strains, Zhu Tao mentioned three ways:

The homology is strengthened. After the initial immunization is completed, the COVID-19 vaccine of the same technical route is used for the booster immunization;

Heterogeneous sequential, after completing the initial immunization, use different technical routes of the COVID-19 vaccine for booster immunization;

Develop new vaccines based on mutant strains, and use new vaccines for primary immunization or booster immunization.

Zhu Tao revealed that CanSino Bio is currently developing a COVID-19 vaccine against the mutant strain. The company pays close attention to the virus mutation and epidemic situation. Once a mutant strain with escape vaccine protection is found, the company’s adenovirus vector technology route has rapid industrialization capabilities and can quickly develop and produce products for new virus strains.

CanSino: COVID-19 Booster shot increases neutralizing antibodies about 8 times

(source:internet, reference only)

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