(AT) 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: 1044

Background: On January 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 experiences increased risk of safety events of interest after receiving Pfizer-BioNTech COVID-19 vaccine.

Methods: Electronic medical record (EMR) data from the 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 9/24/2021. Different methods of analyses for signal detection and evaluation were conducted for 46 pre-specified safety events of interest in addition to a prioritized analysis of myocarditis/pericarditis.

Results: A total of 1,448,043 VHA enrollees with a mean age of 65.2 years received ≥ 1 dose of the Pfizer-BioNTech COVID-19 vaccine.
Using seasonal influenza vaccine as an active comparator, cerebrovascular non-hemorrhagic stroke, acute myocardial infarction, chilblain-like lesions, anaphylaxis, and acute kidney injury were initially detected as potential signals. None remained as a signal following evaluation based on multivariate Poisson regression with a pre-specified signal definition of incidence rate ratio (IRR)>3 and p-value < 0.01.
For myocarditis/pericarditis, there were 29 cases within the 21-day risk interval after either dose of the Pfizer-BioNTech COVID-19 vaccine, and the rate was not significantly different during the comparison interval for both doses (adjusted IRR [95% CI]: 1.07 [0.56, 2.04]). Of the 29 cases, 19 were confirmed through chart review. All 19 individuals had pericarditis and 4/19 (21.1%) had myocarditis. All 4 cases of myocarditis and 17/19 (89.5%) cases of pericarditis had recovered by the date of chart review.

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 signal evaluation analyses. Active safety surveillance is an essential part of pandemic response.
For myocarditis/pericarditis, adjusted analyses comparing events in the risk interval vs. comparison interval among Pfizer-BioNTech COVID-19 vaccine recipients detected no signals, although the small sample size of young men in the VHA population provided limited statistical power.