Long-Term Trends in Human Parainfluenza Virus Types 1, 2, and 3 Infection in Korea (2007-2024)

Abstract

This study investigated the long-term trends in human parainfluenza virus (HPIV) types 1, 2, and 3 in Korea by year, age group, and season. A total of 23,284 nasopharyngeal swabs collected from patients with respiratory symptoms at a tertiary hospital in Korea between 2007 and 2024 were tested for HPIV using real-time reverse-transcription polymerase chain reaction. Of the 23,284 specimens tested, 481 were positive for HPIV-1, 164 for HPIV-2, and 1102 for HPIV-3. HPIV-3 showed the highest incidence between 2010 and 2016, a decline after 2018, a sharp decline during the 2020 COVID-19 pandemic, and a resurgence in 2021. HPIV-1 and HPIV-2 incidence fluctuated between 2007 and 2019, followed by a sharp decline in 2020. HPIV-3 activity peaked in spring and summer, whereas HPIV-1 and HPIV-2 peaked in autumn. For all three types, infection rates were generally highest among children aged 1-12 years, followed by those in infants, but infection rates varied significantly by type, year, season, and age group. These findings emphasize targeted pediatric prevention, predictive modeling of seasonal peaks, and continued molecular surveillance to clarify the genetic and antigenic diversity of HPIV types after the pandemic, supporting the Sustainable Development Goals (SDG 3 for Good Health and Well-Being).

Keywords: COVID-19 pandemic; human parainfluenza virus (HPIV); seasonality; sustainable development goals (SDG 3: good health and well-being).

Figure 1

Annual positivity rate and absolute case counts of human parainfluenza virus (HPIV) types 1–3 detected in nasopharyngeal specimens from patients with respiratory symptoms at a tertiary hospital in Korea from 2007 to 2024. (A) Annual positivity rates (%) of HPIV-1, HPIV-2, and HPIV-3 as a proportion of samples tested. (B) Annual number of laboratory-confirmed positive cases (n) for each HPIV type during the same period. HPIV-1: red line; HPIV-2: blue line; and HPIV-3: green line.

Figure 2

Seasonal distribution of HPIV-1, HPIV-2, and HPIV-3 positivity rates in Korea (2007–2024). The heatmap illustrates the seasonal variation in positivity rates for HPIV-1, HPIV-2, and HPIV-3. The highest activity of HPIV-3 was observed during spring and summer, whereas HPIV-1 and HPIV-2 peaked in autumn. Color intensity corresponds to the positivity rate (%).

Figure 3

Age-specific positivity rates of human parainfluenza virus (HPIV) types 1–3 in Korea, 2007–2024. The bar chart presents the age-specific positivity rates (%) of HPIV-1, HPIV-2, and HPIV-3 detected in nasopharyngeal specimens collected between 2007 and 2024. The age groups, infants (<1 year), children (1–12 years), adolescents (13–18 years), adults (19–64 years), and older adults (≥65 years) are shown on the X-axis, and the positivity rates (%) are shown on the Y-axis. Bars are color-coded by virus type: HPIV-1 (red), HPIV-2 (blue), and HPIV-3 (green). The numerical values above each bar indicate the corresponding positivity rate (%) for that age group.