Associations of COVID-19 vaccination with risks for post-infectious cardiovascular complications: an international cohort study in cancer patients with SARS-CoV-2 infection

Background: Whether COVID-19 vaccination is associated with risks for cardiovascular complications after SARS-CoV-2 infection in patients with cancer is unknown. The objective of this study was to investigate the associations between the two. Methods: This registry (COVID-19 and Cancer Consortium)-based retrospective cohort study included patients with laboratory-confirmed SARS-CoV-2 infection from the United States, Canada, and Mexico between April 2021 and December 2022. Patients without COVID-19 vaccination were assigned to the unvaccinated group and patients with ≥2 doses of COVID-19 vaccination were assigned to the fully-vaccinated group. The primary outcome was a composite of post-infectious cardiac complications, including acute myocardial infarction, other ischemic heart disease, atrial fibrillation, ventricular fibrillation, other arrhythmias, cardiomyopathy, and congestive heart failure. The secondary outcome was a composite measure of post-infectious cardiovascular events, comprising of the cardiac complications along with pulmonary embolism, deep vein thrombosis, superficial vein thrombosis, other thrombosis, and cerebrovascular stroke. Multivariable logistic regression was used for data analysis. Findings: A total of 2729 patients were included for analyses, with 1382 in the unvaccinated group and 1347 in the fully-vaccinated group. The median age of the study population was 65 (interquartile range (IQR), 55–74) years. Overall, 1534 (56.0%) were women; 1272 (47%) were never smokers; 1639 (60%) were not obese; 2043 (75%) had stable cancer, and 446 (16%) took anticoagulants at baseline. The primary and secondary analyses showed lower risks of cardiac complications and cardiovascular events in the fully-vaccinated group, with adjusted odds ratios (aOR) of 0.66 (95% confidence interval (CI), 0.48–0.89) and 0.76 (95% CI, 0.59–0.99), respectively. The protective trend with COVID-19 vaccination was observed across infections with different dominant SARS-CoV-2 strains and in patients with or without anticoagulant use. Interpretation: COVID-19 vaccination was associated with a reduced risk of cardiac complications and cardiovascular events by 34% and 24%, respectively, after SARS-CoV-2 infection in patients with cancer. Funding: National Institutes of Health USA; National Science and Technology Council of Taiwan.