Comparisons of the rate of acute myocardial infarction between COVID-19 patients and individuals received COVID-19 vaccines: a population-based study

Background Both Coronavirus Disease-2019 (COVID-19) infection and COVID-19 vaccination have been associated with the development of acute myocardial infarction (AMI). This study compared the rates of AMI after COVID-19 infection and among the COVID-19 vaccinated populations in Hong Kong. Methods This was a population-based cohort study from Hong Kong, China. Patients with positive real time-polymerase chain reaction (RT-PCR) test for COVID-19 between January 1 st , 2020 and June 30 th , 2021 were included. The data of the vaccinated and unvaccinated population was obtained from the “Reference Data of Adverse Events in Public Hospitals” published by the local government. The individuals who were vaccinated with COVID-19 vaccination prior the observed period (December 6 th , 2021 to January 2nd, 2022) in Hong Kong were also included. The vaccination data of other countries were obtained by searching PubMed using the terms [“COVID-19 vaccine” AND “Myocardial infarction”] from its inception to February 1 st , 2022. The main exposures were COVID-19 test positivity or previous COVID-19 vaccination. The primary outcome was the development of AMI within 28 days observed period. Results This study included 11441 COVID-19 patients, of whom 25 suffered from AMI within 28 days of exposure (rate per million: 2185; 95% confidence interval [CI]: 1481-3224). The rates of AMI were much higher than those who were not vaccinated by the COVID-19 vaccine before December 6 th , 2021 (rate per million: 162; 95% CI: 147-162) with a rate ratio of 13.5 (95% CI: 9.01-20.2). Meanwhile, the rate of AMI was lower amongst the vaccinated population (rate per million: 47; 95% CI: 41.3-53.5) than COVID-19 infection with a rate ratio of 0.02 (0.01, 0.03). Regarding post-vaccination AMI, COVID-19 infection was associated with a significantly higher rate of AMI than post-COVID-19 vaccination AMI in other countries. Conclusions COVID-19 infection was associated with a higher rate of AMI than the vaccinated general population, and those immediately after COVID-19 vaccination.