The U.S. Centers for Disease Control and Prevention (CDC) have published results from a study that used PCORnet®, the National Patient-Centered Clinical Research Network, to better understand the comparative risks of cardiac complications among more than 800,000 patients who tested positive for COVID-19, and more than 4 million children and adults who received mRNA COVID-19 vaccines. The study found that adolescents and young adults who tested positive for COVID-19 were more likely to experience myocarditis, inflammation of the heart, or pericarditis, inflammation of the tissue surrounding the heart, than same aged individuals who received mRNA COVID-19 vaccines.
“The results of this study give important context to concerns about the link between heart conditions and mRNA COVID-19 vaccination,” said Adi Gundlapalli, MD, PhD, Chief Public Health Informatics Officer of CDC’s Center for Surveillance, Epidemiology, and Laboratory Services and senior author of the paper. “The data show that while rare adverse events can occur, COVID-19 vaccines are safe — and, importantly, the risk of experiencing a cardiac complication as a result of COVID-19 infection is much greater than the risk of these events as a result of vaccination.”
While other studies have explored the risk of cardiac complications after infection and vaccination, this study was the largest to date to explore this relationship in the United States. It investigated risk across a wider range of ages, including children as young as 5 years of age into adulthood. “This study provides critical information to parents, clinicians, and policymakers. Much of the information about cardiac complications has only mentioned vaccines. There is a real risk after COVID-19 as well, and these risks need to be discussed together,” Deepika Thacker, MD, a pediatric cardiologist with the Nemours Children’s Health System.
The study was a collaborative effort from investigators at CDC and PCORnet, a distributed research “network of networks” connecting health records across more than 60 healthcare systems in the U.S.
This study analyzed electronic health record information from 40 PCORnet-partnered health care systems to look for patterns across adolescents and young adults who either tested positive for SARS-CoV-2, the virus that causes COVID-19, or received any dose of the Pfizer-BioNTech or Moderna mRNA COVID-19 vaccines between January 1, 2021, and January 31, 2022. The study team looked for patients with near-term (within 7, 21, or 42 days) diagnoses of myocarditis, pericarditis, or multisystem inflammatory syndrome (MIS), a rare but serious condition linked to SARS-CoV-2 infection mostly in younger populations.
This study found a myocarditis or pericarditis incidence of 0 to 35.9 cases per 100,000 among males and 0 to 10.9 among females within 21 days of receiving a first dose, second dose, or unspecified dose of mRNA COVID-19 vaccine across age groups. The incidence was significantly higher among those infected with SARS-CoV-2, which was found to be 17.6 to 114.0 cases per 100,000 for males and 10.8 to 61.7 per 100,000 for females. The risk of myocarditis or pericarditis within 21 days was 2- to 20-times as high after SARS-CoV-2 infection than after mRNA COVID-19 vaccination for males and females across all age groups and vaccine doses.
“CDC and PCORnet are playing an important role in ensuring that the public has the information they need to weigh the benefits and risks of vaccination compared to becoming infected with COVID-19 and subsequent complications,” said Dr. Jason Block, a general internal medicine physician at the Harvard Pilgrim Health Care Institute and the lead author of the study.
“Anyone on the fence about vaccination should gain confidence from these findings that the risk of myocarditis or pericarditis from the mRNA COVID-19 vaccines is very small. Getting vaccinated against COVID-19 is the best way for people to reduce their risk for infection and for cardiac complications associated with COVID-19.”