The first reason is that there is no Anhui zhifei vaccine in the guidelines for strengthening immunization issued in many places.
According to the guidelines issued by Yunnan, Anhui, Guizhou, Guangxi, Beijing, Heilongjiang, Hunan, Hubei and other places, there are four vaccine booster manufacturers in COVID-19, namely Beijing Biological Products Research Institute Co., Ltd., Beijing Kexing Zhongwei Biotechnology Co., Ltd., Wuhan Biological Products Research Institute Co., Ltd. and Tianjin Kangxinuo Biological Co., Ltd., and there is no Anhui Zhifeilong Kyle Biopharmaceutical Co., Ltd., so the fourth booster vaccine in zhifei, Anhui Province has not been vaccinated at present.
Reason 2: The production technology route and action principle of zhifei are different from other vaccines.
The technical route of production in zhifei, Anhui Province is recombinant subunit vaccine, which needs three shots, and the validity period after inoculation is relatively long, which can reach two years. Other vaccines are inoculated with one or two injections, and the validity period is about half a year, which is why it takes at least half a year to strengthen immunization after the whole vaccination.
Reason 3: The effective rate of zhifei is different from other vaccines.
The effective rate of the third vaccination in zhifei, Anhui Province can reach 97%, but the effective rate of general vaccination is not as high as that in zhifei, Anhui Province. However, after intensive vaccination with the original vaccine, the level of neutralizing antibody of the vaccinated person increased rapidly and greatly. Although the antibody level decreased after 6 months of intensive vaccination, the lowest value of the decrease was still higher than the peak value after two or one doses of vaccine, which is one of the reasons why it is necessary to strengthen vaccination.