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Hum Vaccin Immunother
Hum Vaccin Immunother
Human Vaccines & Immunotherapeutics
2164-5515
2164-554X
Taylor & Francis

10.1080/21645515.2024.2404290
2404290
Version of Record
Letter to the Editor
Coronavirus
Comment on “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”
A. SHARIFAN
HUMAN VACCINES & IMMUNOTHERAPEUTICS
https://orcid.org/0000-0003-0571-5964
Sharifan Amin
Department for Evidence-based Medicine and Evaluation, University for Continuing Education Krems , Krems, Austria
CONTACT Amin Sharifan aminsharifan@gmail.com Department for Evidence-Based Medicine and Evaluation, University for Continuing Education Krems, Dr. Karl Dorrekstrasse 30, Krems 3500, Austria.
23 9 2024
2024
23 9 2024
20 1 2404290Integra20 9 2024
Integra20 9 2024
© 2024 The Author(s). Published with license by Taylor & Francis Group, LLC.
2024
The Author(s)
https://creativecommons.org/licenses/by-nc/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. The terms on which this article has been published allow the posting of the Accepted Manuscript in a repository by the author(s) or with their consent.

KEYWORDS

COVID-19
SARS-CoV-2 variants
vaccines
health policy
Immunity
heterologous
letter
antimicrobial stewardship
The author(s) reported there is no funding associated with the work featured in this article.
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pmcDear Editor,

I have read with great interest the article by Zhang et al. that was published in Human Vaccines & Immunotherapeutics.1 The authors have conducted a systematic review and meta-analysis to investigate the efficacy of two doses of inactivated coronavirus disease 2019 (COVID-19) vaccines in persons with no prior immunization, along with the effectiveness of homologous or heterologous COVID-19 booster regimens in healthy people who had already received a primary vaccination series with two doses of an inactivated vaccine, on various outcomes.

On May 5, 2023, the global health emergency of the COVID-19 pandemic was declared to be over by the World Health Organization (WHO), and although the healthcare sectors, besides the public, may have endured the emergency phase of the COVID-19 pandemic, infectious endemics of severe acute respiratory syndrome 2 (SARS-CoV-2) around the globe are predicted, and this worldwide threat persists.2,3 After the emergence of the SARS-CoV-2 Omicron variant, the pandemic took a different trajectory, and the new subvariants developed the ability to escape immunity acquired from infections with lineages before the Omicron variants.4,5 Vaccine-induced immunity may reduce the need for antiviral agents in managing SARS-CoV-2 infections by enhancing the body’s natural defenses. This decreased reliance on antiviral drugs could help prevent the emergence of resistant variants, as it lessens the selective pressure on the virus. Ultimately, prioritizing vaccination can contribute to more effective and sustainable strategies for managing the pandemic while aligning with antimicrobial stewardship principles.6 As a result, several investigations support the development and administration of updated vaccines against COVID-19.7–9 Furthermore, in their interim guidance, the WHO Strategic Advisory Group of Experts on Immunization recommends an additional COVID-19 vaccine booster dose for several groups, and older adults, as well as those with significant underlying conditions or severe obesity, are among the high-priority-use group.10 Taken together, the accumulating evidence for the administration of booster vaccines underscores the importance of the work conducted by Zhang et al.1

In their conclusion, the authors have stated, “the results of our study indicated that whether heterologous or homologous COVID-19 boosters provided good protection, with heterologous boosters being more desirable.” While this conclusion may have a profound impact on future guidelines on using COVID-19 vaccines, I respectfully urge that “either” should be used instead of “whether” for greater accuracy and persuasiveness.

Dr. Amin Sharifan is a PhD candidate at the University for Continuing Education Krems. He is also a member of the Cochrane Early Career Professionals Steering Group. He combines his expertise in evidence-based methodologies and experience as a hospital pharmacist to advance evidence-based medicine and public health. Dr. Sharifan’s research interests span non-communicable diseases, infectious diseases, and acute care, which reflect his commitment to addressing critical health challenges through evidence-based approaches. His work aims to bridge the gap between research and practice to ensure that evidence-based practices are effectively implemented in clinical settings to improve patient outcomes and public health initiatives. As a volunteer, he is also an active peer-reviewer for various academic journals and has served as a reviewer for several conferences, including IDWeek and Global Evidence Summit, along with the UNDP Bureau for Policy and Programme Support to the Sustainable Development Goals.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions statement

AS conceptualized, designed, retrieved data, drafted the paper, and revised it critically for intellectual content, and he agrees to be accountable for all aspects of the work.
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References

1. Zhang X, Xia J, Jin L, Wu Y, Zheng X, Cao X, Meng X, Li J, Zhu F. 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. Hum Vaccin Immunother. 2023;19 (2 ):2221146. doi:10.1080/21645515.2023.2221146.37344370
2. WHO director-general’s opening remarks at the media briefing – 5 May 2023. [accessed 2023 Sep 5]. https://www.who.int/director-general/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing---5-may-2023.
3. Markov PV, Ghafari M, Beer M, Lythgoe K, Simmonds P, Stilianakis NI, Katzourakis A. The evolution of SARS-CoV-2. Nat Rev Microbiol. 2023;21 (6 ):361–2. doi:10.1038/s41579-023-00878-2.37020110
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6. Sharifan A. COVID-19 and the functionality of antivirals: the day after tomorrow. Health Secur. 2022;20 (3 ):270–1. doi:10.1089/hs.2022.0073.35723880
7. Zou J, Kurhade C, Patel S, Kitchin N, Tompkins K, Cutler M, Cooper D, Yang Q, Cai H, Muik A, et al. Neutralization of BA.4–BA.5, BA.4.6, BA.2.75.2, BQ.1.1, and XBB.1 with bivalent vaccine. N Engl J Med. 2023;388 (9 ):854–7. doi:10.1056/NEJMc2214916.36734885
8. Li D, Duan M, Wang X, Gao P, Zhao X, Xu K, Gao GF. Neutralization of BQ.1, BQ.1.1, and XBB with RBD-Dimer vaccines. N Engl J Med. 2023;388 (12 ):1142–5. doi:10.1056/NEJMc2216233.36856580
9. Carr EJ, Wu MY, Gahir J, Harvey R, Townsley H, Bailey C, Fowler AS, Dowgier G, Hobbs A, Herman L, et al. Neutralising immunity to omicron sublineages BQ.1.1, XBB, and XBB.1.5 in healthy adults is boosted by bivalent BA.1-containing mRNA vaccination and previous omicron infection. Lancet Infect Dis. 2023;23 (7 ):781–4. doi:10.1016/S1473-3099(23)00289-X.
10. World Health Organization. WHO SAGE roadmap on uses of COVID-19 vaccines in the context of OMICRON and substantial population immunity: an approach to optimize the global impact of COVID-19 vaccines at a time when Omicron and its sub-lineages are the dominant circulating variants of concern, based on public health goals, evolving epidemiology, and increasing population-level immunity, first issued 20 October 2020, updated: 13 November 2020, updated: 16 July 2021, update: 21 January 2022, latest update: 30 March 2023. World Health Organization; 2023. https://iris.who.int/handle/10665/366671.
