AUTHOR=Wang Wei , Abbaspour Sara , Blumenthal Kimberly G. , Hashimoto Dean M. , Robbins Gregory K. , Klerman Elizabeth B. 

TITLE=Utilizing group-based models to identify adverse event patterns after an intervention

JOURNAL=Frontiers in Medicine

VOLUME=Volume 12 - 2025

YEAR=2025

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2025.1637091

DOI=10.3389/fmed.2025.1637091

ISSN=2296-858X

ABSTRACT=BackgroundStandard adverse event (AE) monitoring only records whether events occur after the intervention, and not whether these events vary over time.ObjectiveTo test whether there were statistically distinct time-varying trajectories of AE (e.g., “side effects”) after an intervention and identify characteristics of individuals associated with these patterns.DesignGroup-based trajectory models applied to an observational study of individuals who received one or two doses of a mRNA COVID-19 vaccine (i.e., the intervention).Participants50,484 healthcare personnel who received their vaccinations within the Mass General Brigham (MGB) healthcare system.InterventionsVaccination.Main measuresAllergic and non-allergic AE for 1–3 days after each of two COVID-19 vaccinations.Key resultsTrajectories models identified distinct groups with different trajectories after intervention: two groups after the first vaccination and five groups after the second vaccination. These groups differed by demographics, age, prior prescription for epinephrine auto-injectors, prior COVID-19 history, time-of-day of vaccination, and vaccine manufacturer.ConclusionSeveral different time-based trajectories after the intervention (e.g., first two COVID-19 vaccinations) were noted; individuals in these groups varied by demographic and clinical criteria. These time-based methods may be able to identify groups at higher risk of future adverse reactions, provide a basis for future studies of the physiology underlying these risk differentials, and improve counseling surrounding interventions associated with AEs. We suggest that trajectory-based methods be added to post-intervention surveillance.