Background: Assessing the quality of evidence from vaccine clinical trials is essential to ensure the safety and efficacy of the vaccine and further enhance public acceptance. This study aims to summarize and critically evaluate the quality of harm reporting on randomized controlled trials for the COVID-19 vaccine and determine the factors associated with reporting quality. Methods: We systematically searched the literature using PRISMA guidelines for randomized controlled trials (RCT) on COVID-19 Vaccine until 30 December 2021. Published articles were searched from electronic databases such as PubMed, Science Direct, Google Scholar, and Bibliovid. Bias analysis was performed using RoB-2 tools. The quality of reporting was assessed by the Consolidated Standards of Reporting Trials (CONSORT) harm extension modified into 21 items. Results: A total of 61 RCT studies (402,014 patients) were analyzed. Over half the studies demonstrated adequate reporting (59.02%), and 21 studies (34.4%) reported a low risk of bias. All studies reported death and serious adverse events (AEs), but only six studies mentioned how to handle the recurrent AEs. Reporting of AEs in subgroup analysis was also poor (25%). Conclusion: The RCTs on the COVID-19 vaccine were less biased with good quality on reporting harm based on the modified CONSORT harm extension. However, study quality must be considered, especially for a balance of information between effectivity and safety.