Cardiovascular and Hematologic Complications of COVID-19 Vaccines

COVID-19 is a prothrombotic and cardiac-damaging disease. There are 4 vaccines against COVID-19 currently approved in North America, including the mRNA vaccines by Pfizer and Moderna, and the adenovirus vector vaccines by Johnson and Johnson and AstraZeneca. These vaccines have been proven effective in reducing morbidity and preventing mortality in patients who were exposed to COVID-19 infection, but the vaccines have also been associated with complications. Vaccine-induced thrombotic thrombocytopenia (VITT) has a similar pathogenesis to heparin-induced thrombocytopenia, with an inappropriate immune response leading to platelet activation, consumption of platelets, and thrombosis. It appears to be more common with the adenovirus vector vaccines. Secondary immune thrombocytopenic purpura has been reported with all COVID-19 vaccines and is distinct from VITT because there is no sign of platelet activation or thrombotic events. Myocarditis and pericarditis are often reported in young males following mRNA vaccines and is often associated with a full recovery. The long-term effects of VITT, secondary immune thrombocytopenic purpura, myocarditis, and pericarditis secondary to COVID-19 vaccines have yet to be elucidated. Continued surveillance for these complications after vaccination is crucial for accurate diagnosis and effective management. Patients should consult their physicians regarding repeated vaccine doses after experiencing an adverse effect.