Journal of Vaccine Research 2024, Vol.14, No.4, 196-206 http://medscipublisher.com/index.php/jvr 196 Feature Review Open Access Long-Term Immunogenicity and Safety Profile of mRNA COVID-19 Vaccines TianZhao CanSino Biologics Inc., Tianjin, 300462, Tianjin, China Corresponding email: tianzhao@hotmail.com Journal of Vaccine Research, 2024, Vol.14, No.4 doi: 10.5376/jvr.2024.14.0019 Received: 28 Jun., 2024 Accepted: 31 Jul., 2024 Published: 14 Aug., 2024 Copyright © 2024 Zhao, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Zhao T., 2024, Long-Term immunogenicity and safety profile of mRNA COVID-19 vaccines, Journal of Vaccine Research, 14(4): 196-206 (doi: 10.5376/jvr.2024.14.0019) Abstract mRNA COVID-19 vaccines represent a new vaccine technology that triggers an immune response by encoding the spike protein of the SARS-CoV-2 virus. Compared to traditional vaccines, mRNA vaccines offer advantages such as rapid development, strong immunogenicity, and flexibility. However, research on their long-term immunogenicity and safety is still ongoing. This study reviews the long-term immunogenicity and safety of mRNA COVID-19 vaccines, analyzing the persistence of immunity in different populations and potential long-term safety issues. Through a review of recent studies, the effectiveness of mRNA vaccines over time is explored, and the long-term safety in various groups is assessed. Research shows that mRNA vaccines can maintain high immunogenicity for several months post-vaccination, but antibody levels and T-cell responses gradually decrease over time. Immunocompromised patients and organ transplant recipients exhibit weaker immune responses, but a third vaccine dose can significantly enhance their immune response. Overall, mRNA vaccines demonstrate favorable long-term safety, with side effects primarily consisting of mild and transient local and systemic reactions. Exploring the long-term immunogenicity and safety of mRNA vaccines is crucial for public health policy-making and future vaccine development. These studies can help scientists and physicians better understand the protective effects of mRNA vaccines and optimize vaccination strategies to enhance global capacity to respond to the COVID-19 pandemic. Keywords mRNA vaccine; Long-term immunogenicity; Safety; Immunosuppression; High-risk populations 1 Introduction The development of mRNA COVID-19 vaccines marked a significant milestone in the fight against the SARS-CoV-2 virus. These vaccines, such as BNT162b2 developed by BioNTech and Pfizer, utilize lipid nanoparticle-formulated, nucleoside-modified RNA to encode the SARS-CoV-2 spike protein, which is crucial for viral entry into human cells (Polack et al., 2020; Walsh et al., 2020). The rapid development and deployment of these vaccines were driven by the urgent need to curb the global pandemic, leveraging novel mRNA technology that allows for quick adaptation and mass production (Gote et al., 2023). The impact of mRNA COVID-19 vaccines has been profound. According to research, these vaccines have shown high efficacy, significantly reducing the incidence of COVID-19 and its severe outcomes (Chavda et al., 2022). Clinical trials have demonstrated that the BNT162b2 vaccine provides 95% protection against COVID-19 in individuals aged 16 years and older, with a favorable safety profile characterized by mild to moderate side effects such as pain at the injection site, fatigue, and headache (Polack et al., 2020). The widespread administration of mRNA vaccines has played a crucial role in controlling the spread of the virus and alleviating the burden on global healthcare systems. While the short-term efficacy and safety of mRNA COVID-19 vaccines have been well-documented, understanding their long-term immunogenicity and safety is crucial. Long-term immunogenicity refers to the sustained ability of the vaccine to provoke an immune response over an extended period (Hoes et al., 2022), which is essential for ongoing protection against the virus. Safety profiles over the long term are equally important to ensure that no delayed adverse effects emerge as more people receive the vaccine (Feng et al., 2024). Studies have indicated that mRNA vaccines elicit robust immune responses shortly after vaccination, but continuous
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