Delta is here, can domestic vaccines still provide effective protection? Industry insiders: Yes!

In the Nanjing epidemic caused by the "Delta" strain, why are some airport staff, who are the key group for COVID-19 vaccination, still infected? Can the domestic COVID-19 vaccine effectively resist the "Delta" mutant strain? In an environment where mutant viruses are spreading, can herd immunity still be achieved through vaccination?

Facing the "Delta" strain, the inactivated COVID-19 vaccine can still provide effective protection

On the evening of July 29, at the COVID-19 vaccine cooperation enterprise dialogue hosted by the Ministry of Foreign Affairs, Yang Xiaoming, chairman of Sinopharm Group China National Biotec Group, responded to the question of the effectiveness of Sinopharm's COVID-19 inactivated vaccine against the Delta strain. Yang Xiaoming said that by conducting cross-neutralization experiments in the laboratory with the serum of people who were immune after being vaccinated with Sinopharm's COVID-19 inactivated vaccine and multiple COVID-19 variants sweeping the world, it was found that Sinopharm's COVID-19 inactivated vaccine can achieve cross-neutralization against four typical variants, including the "Delta" strain. In other words, Sinopharm's COVID-19 inactivated vaccine can still provide effective protection.

"Although everyone is paying close attention to the pandemic of the 'Delta' strain, because the 'Delta' strain has just been imported into the country, it will take time to verify the overall data on its impact on vaccine effectiveness in an epidemiological setting." Yang Xiaoming pointed out that China Biologic has been closely observing the mutation of the new coronavirus, and will make timely strategic adjustments to vaccine research and development as well as production and supply in response to the mutation of the virus.

Yang Xiaoming introduced that active preparations are being made to deal with virus mutations. Sinopharm Group China Biologic is developing an inactivated vaccine for the variant found in South Africa, which is currently in the animal experiment stage. An inactivated vaccine for the "Delta" variant is also under development. In other technical routes, the development of recombinant protein vaccines and mRNA vaccines for variants is also underway.

At the meeting, Yang Guang, chief commercial officer of Sinovac Biotech, also responded to the effectiveness of Sinovac vaccine against the "Delta" strain. He introduced that Sinovac Biotech has currently obtained samples of multiple global prevalent variants, and has also conducted neutralizing antibody experiments with the serum of Sinovac vaccine recipients and different variants, and has seen significant results.

Yang Guang said that the Sinovac vaccine is currently being widely used in Latin America. Chile recently published real-world protection data showing that the Sinovac vaccine has a significant protective effect in areas where the gamma strain of the new coronavirus is prevalent. Similar results were seen in the serum neutralizing antibody study of the "Delta" strain as with the gamma strain. Sinovac is currently using the "Delta" strain to develop and produce new vaccines, and will further advance this research.

Vaccination can still build up an immune barrier, so there is no need to worry

On July 29, the Boao Forum for Asia released the "Global COVID-19 Vaccine Application Landscape Report" in Beijing. Shao Yiming, chief expert and researcher at the Chinese Center for Disease Control and Prevention, said in an interview with reporters that the Nanjing epidemic is still a small-scale epidemic caused by externally imported viruses in local areas. With strong measures, it is believed that it can be quickly extinguished like some recent local epidemics. At present, the new crown vaccine in the world belongs to the second-level prevention of the WHO's three-level prevention standard, that is, prevention of disease. The situation of Nanjing patients still being infected after vaccination is expected. The "Delta" variant strain has high transmission ability, but it is not terrible. Domestic vaccines can still establish an immune barrier.

Shao Yiming explained that the current COVID-19 vaccines around the world, regardless of whether the protection rate is 90%, 80% or 70%, refer to secondary prevention, not primary prevention. The situation of continued infection after vaccination has also raised some new issues for further strengthening public health prevention and control measures and the use of vaccines. Relevant scientific research is being accelerated, and this situation will gradually decrease.

The transmission coefficient of the "Delta" variant has increased significantly, and some people are worried that it may cause great obstacles to achieving herd immunity through vaccines. "As virologists, we are very concerned about these issues, but we will not panic or be anxious. The reason lies in basic immunity." Shao Yiming said that the global new crown vaccines are currently developed based on the new coronavirus gene sequence that China announced online in January 2020 and shared with the world. The protective effect of the vaccine can form a very strong basic immunity. People who have been vaccinated will have good memory cells in their bodies. When vaccinating again, whether it is to use the vaccine of the early strain or the variant strain to do the reinforcement, it can effectively awaken the memory cells and produce a very good protective effect.

Shao Yiming explained that the formula for calculating the immune barrier is (1-1/R0×100%). The transmission coefficient R0 value of the early strain of the new coronavirus is 3, so about 66% of people need to be vaccinated to form an immune barrier. If R0 is increased to 4, the standard of the immune barrier will also be improved, which is achievable. If the R0 value increases from the current 3 by 20% to 30%, vaccination can still establish an immune barrier, and everyone does not need to worry.