Homologous or heterologous immunization regimens against SARS-CoV-2 after two doses of inactivated COVID-19 vaccine: Comment

Dear Editor, we would like to share ideas on the publication “Effectiveness of homologous or heterologous immunization regimens against SARS-CoV-2 after two doses of inactivated COVID-19 vaccine: A systematic review and meta-analysis.”¹ After initial immunization with two doses of the CoronaVac or Sinopharm COVID-19 vaccines, Zhang et al. assess the effectiveness or efficacy of heterologous or homologous COVID-19 vaccine regimens against COVID-19-related outcomes.¹ Up until October 31, 2022, databases from Cochrane Library, Web of Science, EMBASE, and PubMed were searched.¹ Zhang et al. made notice of this. Although both homologous and heterologous regimens were successful in combating SARS-CoV-2 variations, more data are still required to support our conclusions.¹ The COVID-19 immunization is the most efficient illness prevention method. A COVID-19 immunization has been available for some months. Vaccine administration remains complicated due to the fluctuating COVID-19 epidemic environment and the several local immunization management strategies. In response to the issues with COVID-19 immunization, various attempts have been made to employ an alternative method. The analysis presents numerous alternatives. Some studies back up recent recommendations. Aside from the traditional COVID-19 vaccine administration, a number of alternative COVID-19 vaccine administrations have been identified and used in a variety of settings for a variety of reasons. The study’s findings could imply that both homologous and heterologous booster doses greatly improved the efficacy of COVID-19 vaccines against infection when compared to primary immunization. The study also found that the heterologous mRNA vaccine booster was the most effective against COVID-19 infection, followed by the non-replicating vector vaccine booster, the homologous booster, and the two doses of inactivated vaccine. However, the study cautions that more evidence is needed to corroborate these conclusions, especially if new variations emerge. Furthermore, the study did not assess the safety of the various vaccine regimens, which is an essential factor in vaccine policy and administration. Overall, the study provides useful information about the efficacy of various COVID-19 vaccine regimens, but more research is needed to validate and expand on these findings. The findings of the study have significant implications for vaccine policy and administration, since they imply that heterologous booster doses may be more effective than homologous booster doses or two doses of the same vaccine. Furthermore, the study implies that booster doses of the vaccine may improve its effectiveness against SARS-CoV-2 subtypes. The report does, however, state othat further evidence is needed to corroborate these conclusions.

In fact, if neither the most current clinical signals nor the most recent clinical markers are present, a silent COVID-19 must be ruled out.² It must be investigated if the huge number of COVID-19 doses given to people who have already received vaccinations has an impact on the results. Furthermore, the effects of the anti-SARS-Co-V2 vaccine on a person’s physiologic system seem to depend on their genetic makeup.³ Last but not least, the virus is continuously evolving and creating new strains. Long-term study results can be challenging to understand. Before the findings can be confirmed, more clinical research is necessary.Because the use of heterologous vaccination regimens entails administering a different vaccine for the booster dose than the vaccine used for the main immunization. This method is new, and data on its safety and efficacy for COVID-19 immunization is sparse. As a result, before using this strategy in a therapeutic context, it is critical to thoroughly assess the potential dangers and advantages. Second, the World Health Organization (WHO) has yet to give advice on the use of heterologous COVID-19 vaccination regimens. This means that there is no official support for this method, and it may be unpopular in some healthcare settings. Third, there may be equity concerns with the use of heterologous immunization regimens. If some people get booster doses of certain vaccines while others don’t, it could increase existing health inequalities and violate the concept of universal access to healthcare. As a result, before instituting heterologous vaccination regimens, it is critical to carefully assess the ethical implications of this method, as well as to ensure that it is supported by strong scientific data and guidelines from relevant health authorities.

Authors’ contribution

AK 50% ideas, writing, analyzing, approval

VW 50% ideas, supervision, approval