Vaccines routinely used are extremely safe; however, severe adverse events to vaccines do occur. As vaccination against COVID-19 has begun, adverse events to the vaccine, particularly Guillain-Barré syndrome (GBS), vaccine-induced immune thrombotic thrombocytopenia (VITT)/thrombosis with thrombocytopenia syndrome (TTS), and myocarditis/pericarditis, after COVID-19 vaccination have been reported worldwide. Study hypothesis: there are genetic factors that contribute to increased risks of particular COVID-19 vaccine-induced adverse events. The objective of the study is to determine if there are specific genetic factors strongly associated with each of the COVID-19 vaccine-induced adverse events (i.e., GBS, VITT/TTS, and myocarditis/pericarditis).