Incidence, Severity, and Mortality of Influenza During 2010–2020 in Korea: A Nationwide Study Based on the Population-Based National Health Insurance Service Database

Background The epidemiology of influenza is commonly used to understand and establish relevant health policies for emerging respiratory infections, including coronavirus disease 2019 (COVID-19). However, Korea has no confirmed nationwide data on influenza incidence, severity, and mortality rate. Methods We conducted a cross-sectional study to obtain epidemic data on influenza at the national level using National Health Insurance claims data during 2010 to 2020. Influenza cases were defined as 90-day timeframe episodes based on all inpatient and outpatient claims data with disease code J09, J10, and J11. Influenza incidence, severity, and mortality rate were calculated, and logistic regressions were performed to assess the associations of demographic characteristics and comorbidity with influenza-related hospitalization, severe illness, and death. Results There were 0.4–5.9% influenza cases in the population from 2010 to 2020, with 9.7–18.9%, 0.2–0.9%, and 0.03–0.08% hospitalized, used in the intensive care unit, and dead, respectively. Age-standardized incidence and mortality rates were 424.3–6847.4 and 0.2–1.9 per 100,000 population, respectively. While more than half of the influenza cases occurred in populations aged younger than 20 years, deaths in older than 60 years accounted for more than two-thirds of all deaths. Conclusion This study provided the simplest but most important statistics regarding Korean influenza epidemics as a reference. These can be used to understand and manage other new acute respiratory diseases, including COVID-19, and establish influenza-related policies. Graphical

Incidence, Severity, and Mortality of Influenza During 2010-2020 in Korea: A Nationwide Study Based on the Population-Based National Health Insurance Service Database.

BACKGROUND: The epidemiology of influenza is commonly used to understand and establish relevant health policies for emerging respiratory infections, including coronavirus disease 2019 (COVID-19). However, Korea has no confirmed nationwide data on influenza incidence, severity, and mortality rate. METHODS: We conducted a cross-sectional study to obtain epidemic data on influenza at the national level using National Health Insurance claims data during 2010 to 2020. Influenza cases were defined as 90-day timeframe episodes based on all inpatient and outpatient claims data with disease code J09, J10, and J11. Influenza incidence, severity, and mortality rate were calculated, and logistic regressions were performed to assess the associations of demographic characteristics and comorbidity with influenza-related hospitalization, severe illness, and death. RESULTS: There were 0.4-5.9% influenza cases in the population from 2010 to 2020, with 9.7-18.9%, 0.2-0.9%, and 0.03-0.08% hospitalized, used in the intensive care unit, and dead, respectively. Age-standardized incidence and mortality rates were 424.3-6847.4 and 0.2-1.9 per 100,000 population, respectively. While more than half of the influenza cases occurred in populations aged younger than 20 years, deaths in older than 60 years accounted for more than two-thirds of all deaths. CONCLUSION: This study provided the simplest but most important statistics regarding Korean influenza epidemics as a reference. These can be used to understand and manage other new acute respiratory diseases, including COVID-19, and establish influenza-related policies.

The impact of the COVID-19 pandemic in the healthcare utilization in Korea: Analysis of a nationwide survey.

BACKGROUND: COVID-19 has brought changes in daily life and increased the medical burden. This study aims to evaluate the delays in healthcare services and related factors in the general population during the COVID-19 pandemic. METHODS: We took a nationally representative sample and conducted a mobile phone-based survey. The study was conducted anonymously. Of the 3377 subjects who consented to participate, a total of 2097 finished the survey. The primary outcome was respondents' experiences with delayed (1) health screenings, (2) non-urgent medical visits, (3) medical visits for chronic disease, and (4) emergency visits during the COVID-19 pandemic. RESULTS: Of 2097 respondents, females, residents of the Seoul metropolitan area, those with private insurance, those without chronic diseases, smokers, and drinkers had higher risk of delays in health screening and non-urgent medical visits after adjustment. Among chronic disease patients, those who were over 60 years old (adjusted odds ratio 0.36, 95% CI 0.14-0.92) showed lower risk of delayed medical visit. Residents of the Seoul metropolitan area, those with private insurance, smokers, and drinkers were all associated with experiencing delayed health screening and non-urgent medical visits had higher risk of delays in chronic disease visits and emergent medical visits. CONCLUSIONS: Delayed access to healthcare services is associated with poor outcomes and may cause different complications. Efforts are needed to prevent delays in medical use due to infectious diseases such as COVID-19. Considering the possibility of the emergence of infectious diseases, various countermeasures are needed to prevent delays in medical visit.