During the COVID-19 pandemic, linear mRNA-based vaccines have provided remarkable proof of their capabilities and feasibilities for human protection. However, linear mRNA as therapeutic agents still have certain limitations, such as instability, ultracold storage requirement, immunogenicity without nucleoside modification, and short duration of expression for in vivo administration. Therefore, a better mRNA vaccine design strategy is needed. Coding circular RNA (circRNA) has a 3’-5’ covalently closed ring structure provided them with resistance to exonuclease-mediated degradation and a greater stability at a range of temperatures and longer duration of protein expression compared with linear RNAs. This is a valuable feature in the cases when the therapeutic agent must be administered less frequently, or in smaller doses, which would also minimize side effects. Thus, coding circRNA is considered as next generation of therapeutic modality with potential to treat various human diseases including vaccines to cancers, infectious and degenerative diseases. 1. Linear and CircRNA In Therapeutics 2. The Brief History of CircRNA