Declined Circulation and Seasonal Shifts of Human Coronavirus 229E in the Republic of Korea: Implications for Respiratory Virus Surveillance

Human coronavirus 229E (HCoV-229E) is an alphacoronavirus that typically causes mild upper respiratory infections but remains understudied in terms of its long-term immuno-ecological behavior. Although the COVID-19 pandemic markedly altered human behavior and viral transmission, extended circulation patterns of HCoV-229E remain poorly defined. We analyzed annual, seasonal, and age-specific trends using real-time PCR-based respiratory virus surveillance data from Dankook University Hospital collected between 2007 and 2024. Among 23,284 nasopharyngeal swab specimens, 344 were positive for HCoV-229E (overall positivity, 1.43%). Positivity declined significantly over time (OR per year, 0.916; 95% CI, 0.894-0.939; <i>p</i> < 0.001). Compared with spring (1.04%), positivity was highest in winter (2.69%) and lowest in summer (0.29%) (both <i>p</i> < 0.001), whereas autumn (0.81%) showed no significant difference. Early childhood (1-5 years) demonstrated a higher likelihood of positivity than infants aged 0 years (aOR, 1.51; <i>p</i> = 0.007) and the highest crude positivity rate (1.89%). Although underlying mechanisms were not directly assessed, this long-term analysis documents a persistent decline and attenuation of seasonal dominance in HCoV-229E detection beyond the period of pandemic-related suppression. These findings underscore the value of sustained laboratory-based surveillance in identifying and tracking long-term changes in respiratory virus circulation patterns and in supporting public health monitoring aligned with Sustainable Development Goal 3 (SDG 3).