(273) A Nationwide Survey of mRNA COVID-19 Vaccinee's Experiences on Adverse Events and Its Associated Factors

Publication Number: 1318

Background: Amid the growing concern of COVID-19, vaccines have been widely distributed worldwide under emergency use authorization. However, real-world safety profiles of novel vaccine platforms, mRNA vaccines, still need to be intensified.

Objectives: To identify overall trends and factors associated with participants-reported adverse events (AEs) following mRNA COVID-19 vaccination.

Methods: We conducted a cross-sectional, web-based survey from December 2 to 10 in 2021 with a 2,849 nationwide sampled panel. Study participants were individuals who had elapsed at least two weeks after completing two dosing schedules of COVID-19 vaccination among 18 to 49 years of adults. We weighted the study sample by demographic characteristics (sex, age, and regions) to be representative of the Korean population. The outcome was overall trends of participants-reported AEs following mRNA COVID-19 vaccination and associated factors. Severe adverse events were defined if the participant responded to a hospital visit or hospitalization due to an adverse event. We estimated weighted odds ratios (ORs) with 95% CI using multivariable logistic regression models to identify factors associated with AEs.

Results: Of 2,849 participants (median [IQR] age, 35 [27-42] years; 51.6% male), 90.8% for the first dose and 88.7% for the second dose, reported any AEs, and 3.3% and 4.3% reported severe AE, respectively. Compared to BNT162b2 (Pfizer/BioNTech), AEs and severe AEs following mRNA-1273 (Moderna) were generally higher after the first dose (93.5% vs. 89.9% for any AEs; 4.8% vs. 2.9% for severe AEs) and the second dose (95.0% vs. 87.0% for any AEs; 5.8% vs. 3.9% for severe AEs). There were four cases of myocarditis or pericarditis and one case of anaphylaxis requiring admission or emergency department visit. Occurrence of any AEs was more prevalent in mRNA-1273 (OR, 2.06; 95% CI, 1.59-2.67 versus BNT162b2), the first dose (1.22; 1.02-1.47), female sex (1.88; 1.52-2.32), and those with dermatologic diseases (2.51; 1.32-4.77). Additional factors associated with severe AEs were a history of serious allergic reaction (1.96; 1.06-3.64) and anticoagulant medications use in the past 6 months (4.72; 1.92-11.6).

Conclusions: This nationally representative survey revealed that approximately 90% of young adults experience any AEs following mRNA COVID-19 vaccination. Substantial factors including vaccine types (mRNA-1273), the first dose, female sex, and dermatologic diseases were associated with participant-reported AEs. Our findings could gain visibility for policymakers and physicians to establish vaccination strategies tailored to those susceptible to AEs.