Recently, the national infectious diseases Medical Center, Shanghai Key Laboratory of infectious diseases and biosafety emergency response, Professor Zhang Wenhong's team of Huashan infection and Professor Wang Pengfei's team of School of life sciences of Fudan University jointly evaluated the immune escape characteristics of four subtypes of Omicron mutant after two doses of inactivated vaccine and the third dose of booster vaccination.
Relevant results were published in cell host and microbe magazine (2021 if 21.023) on May 8.
By may, 2022, more than 510million cases of COVID-19 had been reported worldwide. Sars-cov-2 Omicron mutant was first detected in November 2020. At present, it has been widely prevalent all over the world, and there are many sub lineages, named ba 1、BA. 1.1、BA. 2、BA. 3、BA. 4、BA. 5. In addition, recombinant subtypes XD, Xe and XF were also detected recently.
In the last one or two months, BA The infection rate of subtype 2 increased rapidly and became the main epidemic strain in many places recently.
Epidemiological studies show that ba 2 has been detected in more than 40 countries and regions, and its transmission capacity is compared with BA 1 is about 30% higher than that of Ba 1 is twice as high**
In addition, its subtype ba 2.12.1 it contains l452q mutation, which is more detected in the United States and has the advantage of transmission.
This study found that the antibody titer of subjects vaccinated with two doses of inactivated vaccine against Omicron strain decreased by at least 5.3 times compared with the original strain**
Experimental evaluation of four subtypes of pseudovirus showed that for BA Neutralizing antibody titer of 2 and ba 1 similar or lower than ba 1。
After the third dose of homologous (inactivated vaccine) or heterologous vaccination, the antibody titer increased significantly, and the antibody positive rate reached at least 75%
In addition, it is expected that the antibody escape of the three recombinant lineages of XD, Xe and XF is not significantly different from the four Omicron sublines studied, because their s protein is different from Ba Or ba.1 2 same.
In December 2021, Professor Zhang Wenhong's team and Professor Wang Pengfei's team of Huashan infection evaluated Omicron BA in serum samples of two doses of inactivated vaccine and three doses of homologous / heterologous vaccination Neutralization ability of 1 strain.
The study found that the antibody titer of the two inactivated vaccines against the Omicron variant decreased significantly, and the neutralizing antibody titer decreased to 6.04, about 10 times lower than the original strain.
No matter what type of third dose enhancement (inactivated vaccine or recombinant subunit protein vaccine), the positive rate of neutralizing antibody titer of serum samples to Omicron strain reached 100%
This study further confirmed that for the population suitable for vaccination, the promotion of vaccine and intensive needle injection is still one of the effective means to prevent the transmission of novel coronavirus, especially the transmission of Omicron strain.
Although the mortality and severe rate of Omicron strain are lower than those of the original strain and delta strain, it can still lead to an increase in the severe rate of the elderly or immunodeficient population. Therefore, for the population suitable for vaccination, it is very important to further improve the whole process vaccination and strengthen the proportion of vaccination.