The development and production of safe and effective vaccines against coronavirus disease 2019 (COVID-19) provides hope for controlling the current pandemic. Adverse events following immunization are unwanted responses or unintended events that must be carefully monitored, as all vaccines, including those developed against SARS-CoV-2, are required to meet safety criteria for administration in humans. Information was collected from the PubMed/Medline database during the months of August 2020 to November 2021. Most adverse events reported in clinical trials were mild or moderate; however, thrombotic events associated with some viral vector-based vaccines against COVID-19 were identified in follow-up studies, although completion of the various ongoing studies and post-marketing surveillance is required to determine all potential adverse events, as well as those of special interest.