COVID-19 vaccine safety profile in Republic of Korea, February 26, 2021 through April 30, 2022.

Background: As of June, 2022, five coronavirus disease 2019 (COVID-19) vaccine brands were used for the national immunization program. The Korea Diseases Control and Prevention Agency has enhanced vaccine safety monitoring through a passive, web-based reporting system and active, text message-based mornitoring. Purpose: This study described the enhanced safety monitoring system of COVID-19 vaccines, and analyzed the frequencies and types of AEs among five brands of COVID-19 vaccines. Methods: AEs reports through the web-based Adverse Events Reporting System in COVID-19 Vaccination Management System and the text message-based among recipients were analyzed. AEs were classified as non-serious AEs and serious AEs (e.g., death and anaphylaxis). AEs were classified as non-serious AEs and serious AEs (e.g., death and anaphylaxis). AE reporting rates were calculated based on the number of COVID-19 vaccine dose administered. Results: A total of 125,107,883 doses were administered in Korea from February 26, 2021 to June 4, 2022. Among them, a total of 471,068 AEs reported, of which 96.1% were non-serious AEs and 3.9% were serious AEs. Among the 72,609 participants in the text message-based AE monitoring, a higher AE rate was reported in the 3rd dose compare to primary doses in both local and systemic reactions. A total of 874 cases of anaphylaxis (7.0 per 1,000,000 doses), four cases of TTS, 511 cases of myocarditis (4.1 per 1,000,000 doses) and 210 cases of pericarditis (1.7 per 1,000,000 doses) were confirmed. A total of seven fatal cases were associated with COVID-19 vaccination (1 TTS case and 5 myocarditis cases). Conclusions: Young adult and female sex were related with a higher reported rate of AEs with COVID-19 vaccines, most of the reported AEs of COVID-19 vaccines was non-serious AEs of mild intensity.

COVID-19 vaccination-related myocarditis: a Korean nationwide study.

AIMS: A comprehensive nationwide study on the incidence and outcomes of COVID-19 vaccination-related myocarditis (VRM) is in need. METHODS AND RESULTS: Among 44 276 704 individuals with at least 1 dose of COVID-19 vaccination, the incidence and clinical courses of VRM cases confirmed by the Expert Adjudication Committee of the Korea Disease Control and Prevention Agency were analyzed. COVID-19 VRM was confirmed in 480 cases (1.08 cases per 100 000 persons). Vaccination-related myocarditis incidence was significantly higher in men than in women (1.35 vs. 0.82 per 100 000 persons, P < 0.001) and in mRNA vaccines than in other vaccines (1.46 vs. 0.14 per 100 000 persons, P < 0.001). Vaccination-related myocarditis incidence was highest in males between the ages of 12 and 17 years (5.29 cases per 100 000 persons) and lowest in females over 70 years (0.16 cases per 100 000 persons). Severe VRM was identified in 95 cases (19.8% of total VRM, 0.22 per 100 000 vaccinated persons), 85 intensive care unit admission (17.7%), 36 fulminant myocarditis (7.5%), 21 extracorporeal membrane oxygenation therapy (4.4%), 21 deaths (4.4%), and 1 heart transplantation (0.2%). Eight out of 21 deaths were sudden cardiac death (SCD) attributable to VRM proved by an autopsy, and all cases of SCD attributable to VRM were aged under 45 years and received mRNA vaccines. CONCLUSION: Although COVID-19 VRM was rare and showed relatively favorable clinical courses, severe VRM was found in 19.8% of all VRM cases. Moreover, SCD should be closely monitored as a potentially fatal complication of COVID-19 vaccination.

The incidence and clinical characteristics of myocarditis and pericarditis following mRNA-based COVID-19 vaccination in Republic of Korea adolescents from July 2021 to September 2022.

OBJECTIVES: Age-specific information regarding myocarditis/pericarditis in adolescents following mRNA-based coronavirus disease 2019 (COVID-19) vaccination in Asia remains insufficient. This study investigated the incidence and clinical characteristics of myocarditis/pericarditis in Republic of Korea adolescents after mRNA-based COVID-19 vaccination. METHODS: This retrospective descriptive study utilized patient data from the Korea Immunization Management System. Incidence rates were calculated according to age and sex. Clinical characteristics (symptoms/signs, laboratory values, and imaging results) were compared between mild and severe cases. RESULTS: Between July 19, 2021 and September 30, 2022, 3,728,224 individuals aged 12 to 19 years received 6,484,165 mRNA-based COVID-19 vaccines, and 173 cases met the case definition for myocarditis/pericarditis: 151 mild (87.3%) and 22 severe (12.7%). The incidence was 3.8-fold higher in males than in females. Troponin I/ troponin T was elevated in 96% of myocarditis cases, demonstrating higher sensitivity than creatine kinase-myocardial band (67.6%) or C-reactive protein (75.2%). ST-segment or Twave on electrography abnormalities were found in 60.3% (85/141). Paroxysmal/sustained atrial/ventricular arrhythmias were more common in severe than in mild cases (45.5% vs. 16.8%, p=0.008). Edema on T2-weighted magnetic imaging occurred in 21.6% (8/37) and 62.5% (5/8) of mild and severe cases, respectively (p=0.03). Abnormal pericardial fluid collection or pericardial inflammation was found in 75.4% of pericarditis cases (49/65). CONCLUSION: Myocarditis/pericarditis occurred in rare cases following mRNA-based COVID-19 vaccination. Most cases were mild, but the incidence was higher in adolescent males and after the second dose. As bivalent severe acute respiratory syndrome coronavirus 2 mRNA vaccination started in Republic of Korea in October 2022, the post-vaccination incidence of myocarditis/pericarditis should be closely monitored, considering clinical characteristics.

2019 Tabletop Exercise for Laboratory Diagnosis and Analyses of Unknown Disease Outbreaks by the Korea Centers for Disease Control and Prevention.

OBJECTIVES: The Korea Centers for Disease Control and Prevention has published "A Guideline for Unknown Disease Outbreaks (UDO)." The aim of this report was to introduce tabletop exercises (TTX) to prepare for UDO in the future. METHODS: The UDO Laboratory Analyses Task Force in Korea Centers for Disease Control and Prevention in April 2018, assigned unknown diseases into 5 syndromes, designed an algorithm for diagnosis, and made a panel list for diagnosis by exclusion. Using the guidelines and laboratory analyses for UDO, TTX were introduced. RESULTS: Since September 9th, 2018, the UDO Laboratory Analyses Task Force has been preparing TTX based on a scenario of an outbreak caused by a novel coronavirus. In December 2019, through TTX, individual missions, epidemiological investigations, sample treatments, diagnosis by exclusions, and next generation sequencing analysis were discussed, and a novel coronavirus was identified as the causal pathogen. CONCLUSION: Guideline and laboratory analyses for UDO successfully applied in TTX. Conclusions drawn from TTX could be applied effectively in the analyses for the initial response to COVID-19, an ongoing epidemic of 2019 - 2020. Therefore, TTX should continuously be conducted for the response and preparation against UDO.

COVID-19 Public Health Measures During National Assembly Elections of the Republic of Korea.

The general elections for the 21st National Assembly in the Republic of Korea were scheduled for April 15th, 2020, which was during the novel coronavirus disease (COVID-19) outbreak. To ensure a safe election, the Korean Centers for Disease Control and Prevention (KCDC) recommended several public health measures. The KCDC developed key interventions after reviewing the general election strategy that targeted COVID-19 patients and individuals isolating at home. Four voters who participated in the election tested positive, but did not contract COVID-19 during voting. The results demonstrated that the KCDC minimized the spread of infection in the community during the election. The measures implemented by KCDC during the election held under a COVID-19 outbreak cannot be generalized to elections as a whole because cultural and national consciousness vary between countries. Nevertheless, it demonstrates that the systemic strategies and applications against the pandemic can minimize the possibility of viral spread.