Vaccines are vital tools in public health as they play critical roles in preventing and controlling infectious diseases. Vaccine technology has advanced from virus-infected lesions to live attenuated, inactivated or killed pathogens, toxoids, and subunits that consist of only specific pathogen parts needed to elicit an immune response. The progression of virus-like particle vaccines, recombinant viral-vectored vaccines, toxoids, protein or polysaccharide-based vaccines designed to conjugate with a distinct carrier protein to enhance immune reaction is a significant milestone. However, some infectious pathogens can avoid the adaptive immune system, while traditional methods may be unsuitable against non-infectious diseases like cancer. Recent studies have demonstrated the potential of messenger RNA (mRNA) vaccines as an alternative to traditional vaccine approaches. mRNA vaccines contain mRNA that encodes the specific antigen and triggers a directed immune response. The two main forms of mRNA used in the study of mRNA vaccines are conventional non-amplifying mRNA and self-amplifying mRNA (saRNA). This article discusses the mRNA vaccine structure, delivery strategies, and protective functions, focusing on mRNA vaccines’ safety and therapeutic potential. Pre-clinical research has demonstrated the broad utility of mRNA vaccines in animal models. Human clinical trials, however, are still under validation. Hence, further studies will need to focus on adapting reliable results of preclinical trials to human applications. The evidence to date suggests that mRNA vaccines are promising next-generation vaccines and, in the future, clinical trials would transform basic research into mRNA therapeutics in medical practices.
COVID-19 ; mRNA Vaccines ; Safety ; Vaccination