Epidemiological Analysis of Influenza A and RSV-B in Korea : Seasonal and Demographic Trends after COVID-19

다국어 초록 (Multilingual Abstract)

We aimed to investigate the long-term epidemiological characteristics of Influenza A and respiratory syncytial virus subtype B (RSV-B) infections in Korea from 2007 to 2024, focusing on differences by age, sex, and season as well as the influence of the COVID- 19 pandemic on viral transmission dynamics. Using multiplex real-time polymerase chain reaction (PCR) data from 23,284 nasopharyngeal specimens collected at a tertiary hospital, we retrospectively analyzed laboratory-confirmed Influenza A and RSV-B infections and compared positivity rates across demographic and temporal variables. We found that Influenza A showed an overall positivity rate of 5.6%, peaking in winter (14.0%) and reaching its lowest point in summer (0.5%), with higher positivity among adults (7.6%) and older adults (7.9%) but no significant sex-based difference. RSV-B demonstrated a positivity rate of 6.4%, exhibiting distinct peaks in autumn (8.7%) and winter (11.9%) and the highest incidence in infants (12.7%), again without significant sex difference. Both viruses showed a marked decline during the COVID-19 pandemic (2019–2022) and a resurgence thereafter, suggesting that non-pharmaceutical interventions and social behavior changes substantially influenced their transmission. We conclude that both Influenza A and RSV-B exhibit clear seasonality and age-dependent susceptibility, with RSV-B affecting infants most severely and Influenza A predominating in adults and older adults. These findings provide essential baseline evidence for the development of age-targeted vaccination programs, adaptive surveillance systems, and evidence-based public health strategies in the post-pandemic era.

목차 (Table of Contents)

• I. INTRODUCTION 1
• II. MATERIALS AND METHODS 7
• 2.1. Study Design 7
• 2.2. Study subjects and data collection 7
• 2.3. Laboratory Testing Procedures 8
• 2.4. Definition of Variables and Data Classification 8
• 2.5. Statistical Analysis 9
• 2.6. Ethical Considerations 9
• 2.7. Summary Schematic and Study Flow 9
• 2.8. Study Limitations and Data Availability 10
• III. RESULTS 13
• 3.1. Characteristics of the Study Population 13
• 3.2. Influenza A : Annual and Seasonal Patterns 13
• 3.3. RSV-B: Annual and Seasonal Patterns 24
• 3.4. Comparative Seasonality 34
• 3.5 Comparative Analysis between Influenza A and RSV-B 38
• 3.6. Impact of the COVID-19 Pandemic 41
• 3.7. Summary and Key Findings 44
• IV. DISCUSSION 51
• V. CONCLUSION 56
• REFERENCES 60
• ABSTRACT(KOREAN) 68