(297) Distinguishing Patterns of Serious Adverse Events with mRNA COVID-19 Vaccines Using Vigibase: A Latent Class Analysis

Publication Number: 1342

Background: Although messenger RNA (mRNA) vaccines were developed and widely utilized in response to the COVID-19 pandemic, it is essential to describe the adverse events (AEs) following immunization.

Objectives: This study aimed to identify the patterns associated with serious AE reports with mRNA coronavirus disease (COVID-19) vaccines on World Health Organization (WHO)’s global scale.

Methods: This study performed a latent class analysis from VigiBase between December 2020 and August 2021. The 10 most frequently system organ class (SOC) terms of medical dictionary for regulatory activities as parameters to estimate were used in the latent class analysis (LCA). The mRNA COVID-19 vaccines were defined as either tozinamernan or elasomeran as the suspected drug of individual case safety reports in J07BX (other viral vaccines) on the Anatomical Therapeutic Chemical code. A serious AE is defined as a report that is associated with death, life-threatening, hospitalization or prolongation, and results of chronic damage/disability. We considered death, life-threatening, and hospitalization to be high-seriousness. The reporting characteristics in accordance with classes were described.

Results: A total of 145,038 spontaneous reports on mRNA COVID-19 vaccines were identified between December 2020 and August 2021 in VigiBase. The most common SOC terms were general disorders and administration site conditions, nervous system disorders, musculoskeletal and connective tissue disorders. Three classes of AE reports were distinguished on LCA. Class 1 accounted for 24% (34,972 reports) of the reports and was distinguished from other classes by being composed AEs of reported time to onset shorter than 1 day (60.2%, 21,042 reports), and reported by consumers (44.8%, 15,679 reports). Class 2 represented about 62% (90,209 reports) of the reports, predominantly with the death (12.9%, 11,620 reports). The reports by physician (23.0%, 4,570 reports), and hospitalization (36.6%, 7,264 reports) were more likely to be in class 3. In addition, an increased high-seriousness risk was observed in class 2 (adjusted odds ratio (aOR) 1.61, 95% confidence interval (CI) 1.55-1.66), and class 3 (aOR 1.90, 95% CI 1.82-2.00) compared with class 1.

Conclusions: Using LCA, we found distinct 3 classes based on the most frequent AEs after COVID-19 vaccines administration. Distinguishing classes had distinct characteristics and observed differences in an increased risk of high-seriousness