COVID-19 vaccine safety: Background incidence rates of anaphylaxis, myocarditis, pericarditis, Guillain-Barré Syndrome, and mortality in South Korea using a nationwide population-based cohort study.

BACKGROUND: To properly assess an association between vaccines and specific adverse events requires a comparison between the observed and background rates; however, studies in South Korea are currently limited. Therefore, in this study, we estimated the background incidence of anaphylaxis, myocarditis, pericarditis, Guillain-Barré syndrome (GBS), and mortality in South Korea. METHODS: A retrospective cohort study was conducted using the National Sample Cohort (NSC) data. Using NSC, the background incidence rate was estimated by dividing the number of episodes during 2009-2019 by the total population by year and then multiplying by 100,000. Using Statistics Korea data, the background mortality rate was estimated by dividing the number of deaths, during 2009-2019 by the standard population for that year and then multiplying by 100,000. Using background mortality rates, we predicted mortality rates for 2021 using autoregressive integrated moving average models. Further, the expected mortality rates were compared with observed mortality rates. RESULTS: The age-adjusted incidence rate (AIR) of anaphylaxis increased from 4.28 to 22.90 cases per 100,000 population (p = 0.003); myocarditis showed no significant increase, changing from 0.56 to 1.26 cases per 100,000 population (p = 0.276); pericarditis increased from 0.94 to 1.88 cases per 100,000 population (p = 0.005); and GBS increased from 0.78 to 1.21 cases per 100,000 population (p = 0.013). The age-adjusted mortality rate decreased from 645.24 to 475.70 deaths per 100,000 population (p <0.001). The 2021 observed/expected mortality rates for overall (ratio: 1.08, 95% confidence interval [CI]: 1.07-1.08), men (ratio: 1.07, 95% CI: 1.07-1.08), and women (ratio: 1.08, 95% CI: 1.07-1.09), were all significantly higher. When stratified by age group, those aged ≥80 (ratio: 1.16, 95% CI: 1.15-1.17), 60-69 (ratio: 1.11, 95% CI: 1.10-1.13), and 20-29 years old (ratio: 1.07, 95% CI: 1.02-1.13) were also significantly higher. CONCLUSION: Through the estimation of background rates related to anaphylaxis, myocarditis, pericarditis, GBS, and mortality, we established a reference point for evaluating the potential excess occurrence of adverse events following COVID-19 vaccination. This reference point serves as substantive evidence supporting the safety profile of COVID-19 vaccines.

Signal detection of COVID-19 vaccines adverse events using spontaneous reports from South Korea.

PURPOSE: Studies on the detection of COVID-19 vaccine signals in South Korea are insufficient. Therefore, to investigate adverse events (AEs) that might be associated with COVID-19 vaccines, signals were detected using spontaneous reports from South Korea. We compared the signals with the vaccine insert lists of the regulators in the four countries. METHODS: Spontaneous reports from 62 sites were collected by the National Medical Center between January 2013 and May 2022. A descriptive analysis of AEs associated with COVID-19 vaccines (Pfizer, Moderna, AstraZeneca, and Janssen) was performed, and the proportional reporting ratio, reporting odds ratio, and information component were calculated. We performed five analyses, with five cases and one control group. RESULTS: During the study period, 68 355 cases were reported, of which 12 485 were COVID-19 vaccine AEs. Injection site pain (2198 cases, 17.6%), myalgia (1552 cases, 12.4%), headache (1145 cases, 9.2%), pyrexia (1003 cases, 8.0%), and fatigue (735 cases, 5.9%) were frequently reported. When comparing all COVID-19 vaccines with other viral vaccines, 20 signals were detected, of which cachexia, dyspepsia, abdominal discomfort, and mood swings were not listed on the vaccine inserts in all four countries. Overall, 20, 17, 29, and 9 signals were detected in vaccines developed by Pfizer, Moderna, AstraZeneca, and Janssen, respectively. CONCLUSIONS: Based on a disproportionate analysis of COVID-19 vaccine AEs using spontaneous reports from South Korea, different signals were detected for each vaccine manufacturer.

Epidemiology and evaluation of adverse drug reactions in a Korean hospital database for spontaneous reports in the period 2009 to 2018.

OBJECTIVE: To evaluate the epidemiology of adverse drug reactions (ADRs) in the Korean population and to identify their characteristics and factors affecting their severity. MATERIALS AND METHODS: The analysis was based on the ADRs reported to the Seoul National University Hospital between 2009 and 2018. Statistical assessment (SPSS Statistics 25) included frequency analysis and the χ2-test. Risk factors were assessed using logistic regression analysis. Results were considered significant at p < 0.05. RESULTS: A total of 44,122 cases were analyzed of which 24,801 (56.2%) cases concerned females and 19,321 (43.8%) males. A total of 47% of cases involved persons aged between 50 and 79 years. Antineoplastic agents, immunomodulating agents, and systemically administered anti-infective agents accounted for 57.6% of all drugs reported. Gastro-intestinal system disorders accounted for the largest proportion (25.8%) of adverse drug reactions reported. A total of 3,429 (7.8%) ADRs were reported as being in the category severe. Multivariate analysis showed that the risk of an ADR being reported as severe is higher in males than in females (OR = 1.25, 95% CI: 1.16 - 1.35), and higher in those aged 0 - 4 years (OR = 1.74, 95% CI: 1.46 - 2.08), in those aged 5 - 19 years (OR = 1.19, 95% CI: 1.07 - 1.31), and in those aged 65 years and over (OR = 1.26, 95% CI: 1.16 - 1.37), compared to those aged 20 - 64 years. DISCUSSION AND CONCLUSION: From a public health perspective, ADRs are important because they are preventable. Important determinants, such as differences in specific age groups and drug classes, for the occurrence of ADRs and the occurrence of severe ADRs in particular, were identified. These determinants need to be carefully monitored in both private medical practices, clinics and hospitals. This monitoring of specific groups will involve close attention factors associated with gender, age group, and drug classes.