Factors related to the serious adverse events in patients visiting the emergency department after ChAdOx1 and mRNA COVID-19 vaccination.

INTRODUCTION: We investigated the clinical characteristics, outcomes and factors related to the serious adverse events (AEs) of patients visiting the emergency department (ED) with various AEs after ChAdOx1 and mRNA COVID-19 vaccination. METHODS: Patients with AEs who visited the ED between March 2021 and September 2021 were selected from three EDs. The clinical data of these patients were collected by retrospectively reviewing medical records. Serious adverse events (AEs) were defined as any adverse medical events that led to hospital admission. RESULTS: A total of 3572 patients visited the ED with AEs; 69.6% were administered mRNA vaccines, and the median (IQR) age was 48 (31-63) years. Regarding chief complaints, chest pain/discomfort (43.7%) was most common in the mRNA vaccines group, while fever (15.8%) was more commonly presented in the ChAdOx1 group. Most patients (93.9%) were discharged from the ED. In multivariate analysis, age ≥70 years, days from vaccination to ED visit ≥8 days, fever and dyspnea as chief complaints were higher independent risk factors for serious AEs (OR 27.94, OR 2.55, OR 1.95 and OR 2.18: p < 0.001, p < 0.001, p = 0.003 and p = 0.003, respectively). CONCLUSION: Most patients who visited the ED with AEs after vaccination were discharged from the ED regardless of the type of vaccine. Emergency physicians need to differentiate serious AEs and consider factors that may require admission to the ED.

Analysis of older adults visiting the emergency department with fever as a suspected Covid-19 vaccine-related adverse reaction: A retrospective multicenter study.

INTRODUCTION: After COVID-19 vaccination was initiated, the number of patients visiting the emergency department (ED) with vaccine-related adverse reactions increased. We investigated the clinical features of older adults (aged 65 years and older) visiting the ED with self-reported COVID-19 postvaccination fever. METHODS: We conducted a retrospective observational study at three EDs between March 2021 and September 2021. Patients who reported adverse reactions, fever (≥37.5 °C) and/or febrile sensation or rigors following COVID-19 vaccination were included. The demographic and clinical data of these patients were collected by reviewing their medical records. RESULTS: A total of 562 patients were selected, and 396 (70.5%) were female. The older adult group included 155 (27.6%) patients, and the median age was 75 (69-79 years). The older adults less frequently had a fever (≥37.5 °C) upon ED presentation (75.5% vs. 85.7%, respectively), used more emergency medical services (43.9% vs. 18.7%, respectively), and visited an ED more frequently during early hours (00:00-06:00) (31% vs. 20.1%, respectively) compared to the younger adults (p = 0.004, p < 0.001 and p = 0.036). Fewer older adults visited an ED within 2 days of fever onset (73.5% vs. 84%) (p = 0.012), and more older adults were admitted for medical conditions other than vaccine-related adverse reactions (32.9% vs. 4.2%) (p < 0.001). Older adults received more thorough testing (laboratory and imaging tests). Among the older adults, the admission rate was associated with age (p = 0.003). CONCLUSION: Older adults presenting with fever as an adverse reaction following COVID-19 vaccination less frequently had a fever upon visiting the ED, required more ED testing, and had higher admission rates for non-vaccination-related medical conditions.