Nucleic acid-based vaccines of COVID-19 and their delivery systems

At the end of 2019, COVID-19 rapidly spread around the world and had a major impact on the global economy and people’s health. According to the World Health Organization (WHO), as of 1 March 2021, more than 100 million people have been diagnosed and 2 million are died because of this pandemic. Fortunately, several vaccines against COVID-19 have been authored for emergency use, including two mRNA vaccines. Nucleic acid-based vaccines, which include mRNA vaccines and DNA vaccines, have shown great advantages in preventing the current COVID-19 than traditional vaccines, such as inactive vaccines, regarding their development rate, manufacture, cost, flexibility for adapting to mutant strains. In this review, the working mechanisms and delivery systems of the nucleic acid-based vaccines and recombinant virus vector-based vaccines are elaborately reviewed and discussed. Moreover, the challenges and future research directions in the field of nucleic acid-based vaccines are also prospected.