6.3 mRNA vaccines
As a result of tremendous advancement in biotechnology, mRNA vaccines represent a significant upgrade over conventional vaccine strategies owing to their higher potency, short production cycles, low-cost manufacturing, and safe administration (Pardi et al., 2018). The sequential events in the process of mRNA vaccine development constitutes antigen selection, sequence analysis and optimization, screening of modified nucleotides, selection of delivery system, immune response and safety evaluation tests (Jahanafrooz et al., 2020). A potential advantage of mRNA vaccines is the convenient availability of a portable mRNA ’printing’ facility for the production of mRNA is large quantities (Saif, 2020). The use of nanotechnology enhances the delivery of mRNA vaccine via intramuscular or intradermal route by using lipid nanoparticle coating (Rauch et al., 2018; Saif, 2020). Thus, a number of major biotech companies have ventured into COVID-19 vaccine development using the advanced nucleic acid vaccine platforms, such Moderna and CureVac (Chen et al., 2020). Since, no mRNA vaccine has been licenced till date its quality and safety testing may take more than the expected time (Zhang et al., 2020). However, with advancement in nucleic acid technologies the nucleic acid vaccine performance in humans has improved due to new modifications and formulations and this approach is expected to ensure the first licenced human nucleic acid vaccine very soon (Chen et al., 2020). In the race of mRNA vaccine development SARS-CoV-2 mRNA vaccine (mRNA-1273) developed by Moderna is the most talked about. It is a lipid nanoparticle- encapsulated mRNA vaccine encoding for S protein. Its manufacturing cost is supported by the Coalition of the Epidemic Preparedness Innovations. This vaccine is currently in phase I open-label dose-ranging trial in humans at Kaiser Permanente Washington Health Research Institute in Seattle and phase II trial to assess the safety, reactogenicity, and immunogenicity is expected in June month of this year (Moderna, 2020). Further, the triangular collaboration between Fudan University, Shanghai Jiaotong University, and Bluebird Biopharmaceutical Company has come up with two different strategies for the development of SARS-CoV-2 mRNA vaccine. The first one targets S protein and RBD of S1 of SARS-CoV-2 and second one uses mRNA to express virus-like particles in vivo (Zhang et al., 2020). The other notable companies and institutions who ventured into SARS-CoV-2 mRNA vaccine development and are in different stages of development are CureVac AG, Stermirna Therapeutics, BDGENE Therapeutics, Guanhao Biotech, ZY Therapeutics Inc., CanSino Biologics Inc., Baylor College of Medicine, University of Texas, etc.