The Zhifei recombinant COVID-19 vaccine approved in Indonesia as a booster can increase neutralizing antibody levels by about 30 times

It is reported that Penny K. Lukito, head of the Indonesian Food and Drug Administration, pointed out that the Zifivax vaccine as a basic immunization is a sequential (heterologous) booster needle of two doses of inactivated COVID-19 vaccine, and 1 dose of Zifivax vaccine after 6 months of inactivated vaccine can increase the neutralizing antibody level by about 30 times.

It has been used urgently in Indonesia last year

Dating back to January 29, 2020, Zhifei Longkema, a wholly-owned subsidiary of Zhifei Biologics, and the Institute of Microbiology of the Chinese Academy of Sciences formally signed the "Framework Agreement on Cooperation Intentions", and the two sides jointly developed a "genetically engineered recombinant subunit vaccine", that is, a recombinant novel coronavirus vaccine (CHO cell).

It is reported that the above projects have been included in the national emergency special project - key research and development plan "public safety risk prevention and control and emergency technical equipment" key special projects, through genetic engineering in the engineering cell expression and purification of pathogen antigen proteins prepared, with completely independent intellectual property rights. This vaccine is developed using recombinant DNA technology, using the receptor binding region (RBD) of the new coronavirus spike glycoprotein (S protein) as an antigen, supplemented by traditional adjuvants, does not carry any form of exogenous label, unique conformation, high immunogenicity, and good safety.

Since December 12, 2020, the above vaccines have successively carried out international multi-center phase III clinical trials in Hunan Province, Uzbekistan, Indonesia, Pakistan and Ecuador in China, and a total of 29,000 people over the age of 18 are planned to be enrolled, and a total of 3 doses of vaccines will be given according to the immunization procedures in 0, 1 and 2 months.

According to the results of the international multicenter Phase III clinical trial, the protective efficacy of the recombinant COVID-19 vaccine (CHO cells) against any severity of COVID-19 is 81.43%, meeting the WHO-required COVID-19 vaccine efficacy standards. The results of the preliminary genotyping analysis showed that the protective efficacy of the vaccine against the Alpha variant was 92.68% and the protective efficacy against the Delta strain was 81.38%.

The results of the above study safety data showed that the incidence of overall adverse events/reactions, no significant difference between the vaccine group and the placebo group, and the safety was good. Zhifei Bio said that the results of the key data of the completed Phase III clinical trial prove that the recombinant new crown vaccine (CHO cells) has a good safety and disease prevention effect in the population that meets the clinical trial protocol.

After one year of research and development and clinical trials, the recombinant new crown vaccine (CHO cells) was registered and listed in Uzbekistan on March 1, 2021, becoming the first recombinant subunit new coronavirus vaccine registered and listed in the world; on March 10, 2021, it was approved for emergency use in China; and on October 7, 2021, it was approved for emergency use in Indonesia.

Ideal candidate for heterologous reinforcers

Since the end of 2021, the Omicron strain has continued to spread around the world, and the epidemic prevention situation is still grim.

On December 20 last year, researchers such as the Institute of Microbiology of the Chinese Academy of Sciences and Academician Gao Fu of the Chinese Center for Disease Control and Prevention jointly released an academic paper on the preprint platform "BioRxiv" pointing out that Aomi Kerong did have serious immune escape in the serum of recovered patients, but among those who received three-dose inactivated vaccines or protein subunit vaccines, the neutralization activity was better preserved.

Among them, the recombinant protein subunit vaccine (ZF2001) group remained 100% positive for the neutralization of the Omikejung strain, and the titer of neutralizing antibody (NAb) was only reduced by 3.1 times, and the data in the ZF2001 (0,1,5) group were better compared with other marketed vaccines.

The article also mentioned that in the ZF2001 group, the second and third injections were extended (4 to 6 months), 100% positive in the neutralization of the Omiljung strain, and the neutralizing antibody (NAb) titer was only reduced by 3.1 times.

62.5% of those who had received three doses of inactivated vaccine, 56.25% of ZF2001 (0, 1, 2 regimens) and 100% of ZF2001 (0, 1, 5 regimens) were positive for TheOmilon neutralizing antibodies. As for neutralizing antibody titers, the serum group of recovered patients declined 17.4 times from prototype to Omikeron. The inactivated vaccine group was reduced by a factor of 5.1, the ZF2001 (0,1,2) group by a factor of 10.6, and the ZF2001 (0,1,5) group had only a 3-fold reduction in the NAB titer of Omikeron.

Based on the above findings, the researchers were prompted to consider that multiple intensifications and extensions of the time interval between vaccinations may be beneficial in dealing with variants of severe variation, such as Omilon. This is consistent with studies of mRNA vaccines, which have shown that people who received three doses of the vaccine were more likely to maintain a neutralizing effect on the Omilon variant.

Earlier, on December 3, 2021, Xie Xiaoliang and Cao Yunlong of Peking University, Jin Ronghua of Capital Medical University and Yu Hongjie of Fudan University jointly published a research paper in the famous international academic journal Cell Research (CellResearch).

It is reported that the purpose of the study of this paper is to evaluate the effect of heterologous third dose ZF2001 or homologous third dose CoronaVac (Coxing vaccine) on vaccine-induced VOC antibodies. The results show that the third dose of coronaVac or ZF2001 vaccine can rapidly induce humoral immunogenicity, while ZF2001 induces a higher humoral immune response, making it an ideal candidate for heterologous enhancers.