(045) Post-Emergency Use Authorization (EUA) Active Safety Surveillance Study among Individuals in the Veterans Affairs Health System Receiving Pfizer-BioNTech Coronavirus Disease 2019 (COVID-19) Vaccine

Publication Number: 382

Background: On 01/29/2021, Pfizer, in collaboration with the US Veterans Health Administration (VHA) and Analysis Group, initiated a study (C4591012) for EUA active surveillance among VHA enrollees.

Objectives: To assess whether the VHA population experience increased risk of safety events of interest after receiving Pfizer-BioNTech COVID-19 vaccine.

Methods: Electronic medical record data from US VHA were used to conduct rapid-cycle, longitudinal, cohort study analyses. The study period began on 12/11/2020 (US FDA EUA approval date) and the data cutoff date for this abstract was 8/31/2022. Different methods of analyses for signal detection and evaluation were conducted for 48 pre-specified safety events of interest and a prioritized analysis of myocarditis/pericarditis.

Results: A total of 1,649,677 VHA enrollees with mean age of 64.3 years received ≥ 1 dose of the Pfizer-BioNTech COVID-19 vaccine.

Using self-controlled risk interval design and historical seasonal influenza vaccine within an active comparator design, cerebrovascular non-hemorrhagic stroke, other acute demyelinating disease, acute myocardial infarction, anaphylaxis, arrhythmia, coronary artery disease, myocarditis, chilblain-like lesions, pulmonary embolism, optic neuritis, heart failure/cardiogenic shock, acute kidney injury, Guillain-Barré syndrome, stress cardiomyopathy, microangiopathy, hemorrhagic disease, and severe COVID-19 disease were initially detected as potential signals. No signal remained after signal evaluation analyses including multivariate Poisson regression and self-controlled case series design with pre-specified signal definition of effect estimate >3 and p-value < 0.01.

For myocarditis/pericarditis, there were 48 cases within the 21-day risk interval after any dose of the Pfizer-BioNTech COVID-19 vaccine, and the rate was not significantly different during the comparison interval for aggregated doses 1-4 (adjusted incidence rate ratio [95% CI]: 0.96 [0.65, 1.42]). Of the 48 cases, 33 were confirmed through chart review, which included 32 (97.0%) individuals with pericarditis, 5 (15.2%) with myocarditis, and 4 (12.1%) with both. The majority of cases recovered by the end of follow-up (mean of 5.8 months).

Conclusions: None of the safety events of interest were found to be associated with Pfizer-BioNTech COVID-19 vaccine based on the signal detection and evaluation analyses. Active safety surveillance is an essential part of pandemic response.

For myocarditis/pericarditis, adjusted analyses comparing events in the risk vs. comparison interval among vaccine recipients detected no signals, although the small sample size of young men in the VHA population provided limited statistical power.