Adverse events following immunization (AEFIs) of COVID-19 vaccine in Samutsakhon Hospital

Abstract

Abstract

Objectives: To analyze the prevalence and characteristics of patients who experienced adverse events following immunization (AEFIs) from COVID-19 vaccines reported to the Adverse Drug Reaction Center in Samutsakhon Hospital classified by seriousness, types of vaccines and dosing schedules.

Methods: This retrospective observational study collected data on all patients received COVID-19 vaccines either who experienced AEFIs during the 30-minute observation period or who were discharged  and revisited the emergency room, the general practice unit or admitted to the inpatient department in Samutsakhon Hospital due to AEFIs. Patients with AEFIs were assessed by physicians and pharmacists. The data in this study were collected from AEFI form-sheets reported to Adverse Drug Reaction center of Samutsakhon hospital and network between February 28, 2021 and June 30, 2022. The data were analyzed by descriptive statistics using frequency and percentage (Each patient may have more than one event).

Results: We found 622 AEFI reports from 620 patients. Most of the patients were female (72.58%). The AEFIs were most frequently found in the age group of 18 to 40 years (49.03%), in who received Sinovac vaccine (41.96%), after the first dose of COVID-19 vaccination (58.52%), and during the period between 30 minutes to 24 hours. The most frequently found AEFI was pruritic rash. The prevalence of total and serious AEFIs were 6.27 and 0.85 events per 10,000 doses, respectively. The most common AEFI from CoronaVac^® (Sinovac), Vaxzevria^® (AstraZeneca), Comirnaty^® (Pfizer) and Covilo^® (Sinopharm) was pruritic rash (3.95, 1.09, 0.64 and 0.34 events per 10,000 doses, respectively) and from Spikevax^® (Moderna) was fever (6.05 events per 10,000 doses). There were 78 reports of serious AEFIs, without causality assessment, from 76 patients who received Vaxzevria^®, CoronaVac^®, Comirnaty^®, Covilo^® and Spikevax^® (28, 24, 19, 4 and 3, respectively), most of which were female (46), in the age group of 41 to 60 years (32) and after the first dose (36). Stroke was the most commonly found serious AEFI (29), followed by anaphylaxis (13), death (13), admission longer than 3 days (7), myocarditis/pericarditis (6), Bell’s palsy (5), coagulation disorder (2), Guillain-Barre syndrome (2) and disability of permanent blindness in one eye (1).

Conclusions: The prevalence of AEFIs from COVID-19 vaccines was 6.27 events per 10,000 doses, which was rare. Most of AEFIs were non-serious. The prevalence of serious AEFIs was 0.85 events per 10,000 doses (without causality assessment), which was very rare. The serious AEFI symptoms were found involving various organ systems and including disability and death. Therefore, close monitoring after COVID-19 vaccination is needed.

Keywords: adverse events following immunization (AEFI), prevalence of AEFI, COVID-19 vaccines