(300) Risk of Myocarditis/Pericarditis After mRNA COVID-19 Vaccination in Commercial Insurance Claims

Publication Number: 1344

Background: Myocarditis/pericarditis (myo/peri) has been observed after mRNA COVID-19 vaccination in several commercial claims databases but quantifying risk in patient subgroups is challenging because event rates are low. Using a large, pre-adjudicated, open claims database with broader capture of myo/peri events may help inform more granular risk assessments of patient subgroups.

Objectives: To estimate the risk of myo/peri after mRNA COVID-19 vaccination in a large US commercial claims dataset.

Methods: We conducted a self-controlled case series study of those 18-64 years old (yo) with record of mRNA COVID-19 vaccination in IQVIA LRxDx OpenClaims data from 12/2020-12/2021 to estimate the risk of incident myo/peri diagnosis in the 28-day risk window following vaccination, both overall and stratified by age and sex. We examined each vaccine (Moderna and Pfizer) and dose (first and second) separately and included a wash-out period (15-day) prior to first dose. For sensitivity analyses, we varied risk windows, and we used only post-exposure risk intervals. For context, we assessed risk of myo/peri after COVID-19 diagnosis using a similar design.

Results: We observed 12,714 and 17,568 myo/peri events among those administered Moderna (N=49,518,140) or Pfizer (N=75,115,773) vaccines at least once, respectively. There 844 events (46 per 100 person years [py]) during exposed risk windows (28-days after 1st or 2nd dose) among those administered Moderna and 1,044 events (31 per 100 py) during exposed risk windows among those administered Pfizer. Adjusting for age, we observed elevated risk after dose one (incidence rate ratio [IRR] 1.40, 95% confidence interval [CI]: 1.27-1.54 for Moderna; IRR 1.42, CI: 1.30-1.55 for Pfizer) and dose two (IRR 2.24, CI: 2.02-2.47 for Moderna; IRR 1.99, CI: 1.87-2.18 for Pfizer). In the age and sex stratified analyses risk was highest among males and younger patients ( < 25 and 26-35 yo) for both Moderna and Pfizer, particularly after their second dose; results were robust to sensitivity analyses. COVID-19 diagnosis was also associated with increased risk after adjusting for age.

Conclusions: In a large, payor-agnostic commercial claims dataset both mRNA COVID-19 vaccines were associated with increased risk of myocarditis/pericarditis. The risk was notably higher among males and those under 35 years old.