The number of cases and disease-dependent deaths continue to increase worldwide due to the COVID-19 infection accepted as a global pandemic by the World Health Organization on March 11, 2020. Therefore, the antivirals used in treatment and vaccines that are the most effective weapons for protection remain the most popular topic on the agenda. There are a few conditions that might have an impact on the course of the pandemic, including the mutation of the virus and losing its ability to cause disease, generating herd immunity by reaching a critical rate of immunized people in the community due to the disease, and ensuring herd immunity through effective vaccination. Vaccine trials, which have started owing to the severity and urgency of the situation we are in, continue highly rapidly and effectively. According to the March 2, 2021 data of WHO, there are 258 vaccine trials, 76 of which are at the clinical phase, and 9 of the vaccine trials that are at the clinical phase are RNA-based vaccines. In our study, it was aimed to investigate RNA-based COVID-19 vaccine candidates and review their current data.