ZENG Guang: A Most Powerful Vaccine Combination is Required in China to Form an Immunologic Barrier

On November 6, at the 4th Hongqiao International Health Technology Innovation Forum, the official event of the 4th China International Import Expo (CIIE), Professor ZENG Guang, a well-known public health and epidemiology expert, pointed out that we must continue to develop new vaccines and adjust strategies, since after being vaccinated with the COVID-19 vaccine, it is inevitable that antibodies will decline.

When talking about the reasons for the severe challenge caused by the Delta mutant strain, ZENG Guang expressed that the Delta mutant strain increases the aerosol transmission component and spreads quickly, which can spread for three to four generations within a week, and there are cases with an incubation period of more than ten or even fifteen days. This has led to a greater difficulty in prevention and control at this stage. Since the main domestic injections are inactivated vaccines against the original strain, infection may still be possible after vaccination. Therefore, the new generation of vaccines should update the antigens to target the latest mutant strains, and the effectiveness should be much better. In addition, people who were previously vaccinated with two doses now need a booster dose, as the third dose can greatly increase the antibody and avoid severe cases.

"It is the time to vigorously promote booster doses to ensure the continuity of immunity, practical experience in various countries has shown that mRNA vaccines or recombinant protein vaccines are more effective as the third dose of sequential vaccination." ZENG Guang said, the most important concern is the safety and inoculation rate during early vaccination, but 3-6 months after vaccination, it depends on the continuity of immunity. On account of the vaccine type is different and the sustainability performance is not the identical, it is the time to inject the booster doses now. There are two ways of injecting booster doses, one is homogenous vaccination, that means the vaccine type of the third dose is the same as that of the first and second doses, which is safe and compatible; the other one is a new practice: heterologous vaccination, for example, inject the third dose of mRNA COVID-19 vaccine or recombinant protein COVID-19 vaccine on the basis of the previous two doses of inactivated COVID-19 vaccine, which can achieve a better performance.

ZENG Guang believes that we need to set up the best combination of COVID-19 vaccines for sustainable development, and such a trend as to what kind of vaccine combination works best shall be explored by the country. In fact, China has many alternative COVID-19 vaccines, and the approval and marketing of various COVID-19 vaccines should be accelerated.