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Microbes & Immunity Homologous versus heterologous COVID-19 vaccines

vaccination regime. Despite there is hesitancy regarding Acknowledgments
how immunogenicity of heterologous vaccines correlates
to vaccine effectiveness against SARS-CoV-2 infections The authors would like to thank the Jeffrey Cheah School
when administered in the real-world environment, a study of Medicine, Monash University Malaysia, for supporting
40
by Khoury et al. elucidated that utilization of neutralizing this study.
antibody titers was a good predictor of immunity against Funding
symptomatic COVID-19 infection. In terms of the
reactogenicity of heterologous vaccines, common local None.
and systemic side effects were experienced and generally
tolerable. In addition, there were no significant vaccine Conflict of interest
related adverse events reported by the studies. The authors declare that they have no competing interests.
The studies included in this scoping review had several Author contributions
limitations. Firstly, the number of participants included was
inconsistent among the studies and, therefore, would affect Conceptualization: Ammu K Radhakrishnan
the precision of results when comparing between groups. Writing – original draft: Samantha Si Mei Khoo
With regards to measuring immunogenicity, the units of Writing – review & editing: Kang Wei Tan, Ashwini
measurement were not congruent among the studies, and Mahendran, Saatheeyavaane Bhuvanendran, Ammu
there were difficulties in determining an accurate unit Kutty Radhakrishnan
conversion due to possible differences in immunoassays
or methods of measurement used between studies. In Ethics approval and consent to participate
addition, the interval between prime and booster doses Not applicable.
was incongruent between studies.
The review process, while synthesizing the following Consent for publication
scoping review, was subject to several limitations. With Not applicable.
regards to study design, most of the included studies were
observational studies (cohort studies, cross-sectional Availability of data
studies), and according to the hierarchy of evidence, the Not applicable.
evidence quality is ranked lower compared to RCTs. In
addition, direct comparisons of data from the studies may References
not give the most precise estimate of the effect and would 1. WHO. COVID-19 Dashboard. World Health Organization;
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5. Conclusion
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Volume 1 Issue 2 (2024) 26 doi: 10.36922/mi.3757