Abstract
The global research and development of mRNA vaccines have been prodigious over the past decade, and the work in this field has been stimulated by the urgent need for rapid development of vaccines in response to an emergent disease such as the current COVID-19 pandemic. Nevertheless, there remain gaps in our understanding of the mechanism of action of mRNA vaccines, as well as their long-term performance in areas such as safety and efficacy. This paper reviews the technologies and processes used for developing mRNA prophylactic vaccines, the current status of vaccine development, and discusses the immune responses induced by mRNA vaccines. It also discusses important issues with regard to the evaluation of mRNA vaccines from regulatory perspectives. Setting global norms and standards for biologicals including vaccines to assure their quality, safety and efficacy has been a WHO mandate and a core function for more than 70 years. New initiatives are ongoing at WHO to arrive at a broad consensus to formulate international guidance on the manufacture and quality control, as well as nonclinical and clinical evaluation of mRNA vaccines, which is deemed necessary to facilitate international convergence of manufacturing and regulatory practices and provide support to National Regulatory Authorities in WHO member states.
Highlights
The prophylactic vaccine candidates use mRNA formulated in lipid nanoparticles (LNPs)
The onset of the pandemic caused by Severe Acute Respiratory Syndrome (SARS)-CoV-2 resulted in massive efforts to develop COVID-19 vaccines via a number of different technologies; due to the rapidity with which mRNA vaccine candidates could be designed and manufactured, they were among the first COVID-19 vaccines to enter clinical trials
A significant advance that led to the rapid expansion of efforts to use mRNA as a platform technology was the discovery by Karikó and Weissman that the use of modified nucleosides resulted in a decrease in the immunostimulatory effects of the in-vitro transcribed mRNA, via a decrease in Toll-like receptor (TLR) stimulation [11]
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Emerging infectious diseases present compelling targets for the nascent technology for a variety of reasons, including the rapidity with which they can be made when faced with a newly discovered pathogen For this reason, targets with candidates in clinical trials have included influenza viruses (H7N9 and H10N8) and Zika virus, and most recently, and most urgently, the causative agent for COVID-19, SARS-CoV-2. The onset of the pandemic caused by SARS-CoV-2 resulted in massive efforts to develop COVID-19 vaccines via a number of different technologies; due to the rapidity with which mRNA vaccine candidates could be designed and manufactured, they were among the first COVID-19 vaccines to enter clinical trials. The R&D Blueprint explicitly seeks to enable early cross-cutting R&D preparedness that is relevant for an unknown “Disease X” This is not an exhaustive list, nor does it indicate the most likely causes of the epidemic. The role WHO has in improving regulatory convergence at the global level by developing standards is discussed, since promoting regulatory convergence is recognized as a key enabler in the R&D Blueprint
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
