What does continuous vaccination mean in COVID-19? Is sequential vaccination in COVID-19 the fourth dose?

Sequential vaccination of vaccines in COVID-19 is an immunization strategy to improve the preventive effect, according to a certain vaccination time interval and dose, and considering the safety of vaccines with different technical routes.

For example, the first two shots are inactivated vaccines, and the third shot is inoculated with recombinant protein vaccine or adenovirus vector vaccine, which belongs to heterogeneous vaccination, that is, sequential vaccination.

What needs to be distinguished is that if the second dose uses different brands of inactivated vaccine, it is only homologous substitution vaccination or mixed vaccination, which cannot be called sequential immunization.

Because of the constant variation of COVID-19, the epidemic prevention effect of single vaccine is not enough. For some viruses with strong variability and difficult to deal with, sequential immunization is needed to achieve better epidemic prevention effect.

Sequential vaccination of COVID-19 vaccine is not the fourth injection, but a new way to strengthen immunization. You can choose vaccines from other production routes, that is, COVID-19 vaccine using any other non-inactivated technology in subsequent booster injections.

COVID-19 vaccine booster always needs to complete three injections, but there is only one injection for continuous vaccination. If the third booster dose is given, it is not necessary to take sequential booster immunization. According to the current immunization results, both homologous immunization and sequential immunization can further improve the immune effect, and it is not necessary to continue taking it.

If the third injection has not been carried out, sequential booster vaccination can be carried out, and the optional vaccine is the recombinant protein vaccine of Anhui Zhifeilong Kyle Co., Ltd. or the adenovirus vector vaccine of Tianjin Kangxinuo Company.

The correct sequential inoculation methods in COVID-19 include inoculation population conditions and inoculation methods.

The conditions of vaccination population include that the age must be above 18, and two doses of inactivated vaccine should be vaccinated. Moreover, according to the existing sequential immunization research, the inactivated vaccine must be COVID-19 inactivated vaccine from Sinopharm Zhongsheng Beijing Company, Beijing Kexing Company and Sinopharm Zhongsheng Wuhan Company, and it has been 6 months since the two doses of inactivated vaccine were inoculated, and the booster immunization has not been carried out.

The inoculation method includes the first shot: Zhongsheng Beijing/Zhongsheng Wuhan/Kexing Zhongwei COVID-19 inactivated vaccine, the second shot: Zhongsheng Beijing/Zhongsheng Wuhan/Kexing Zhongwei COVID-19 inactivated vaccine, and the third shot: recombinant protein vaccine or adenovirus vector vaccine for sequential booster immunization.