Diagnostic Implications of Long-Term Polymerase Chain Reaction Data for Human Metapneumovirus

The aim of this study was to systematically examine the annual, seasonal, age-specific, and gender-specific epidemiological trends of human metapneumovirus (hMPV) infections, utilizing extensive real-world data collected over 18 years through a consistent testing methodology and analytical protocol.

Real-time reverse transcription polymerase chain reaction assay results of patients admitted to Dankook University Hospital (2007 - 2024) were retrospectively analyzed. Descriptive statistics were used to assess annual, age-specific, and seasonal trends in hMPV positivity rates. We further evaluated the feasibility of using these data to establish robust epidemiological surveillance systems and standardized monitoring metrics.

Among 23,284 specimens, 991 (4.2%) were positive for hMPV. The highest annual positivity rates were recorded in 2007 (7.7%) and 2011 (8.1%). Children aged 2 - 11 years exhibited the highest positivity rate (6.0%), with positivity rates declining with increasing age, except for a slight increase in individuals aged ≥ 65 years. Seasonally, infections peaked in spring (11.1%), followed by summer (2.8%), winter (1.4%), and autumn (0.8%). Since the onset of the coronavirus disease 2019 (COVID-19) pandemic (2020 - 2024), the overall positivity rate dropped to 1.6% from 4.7% before the pandemic, accompanied by notable changes in seasonal patterns.

This study revealed significant shifts in hMPV epidemiology following the COVID-19 pandemic, including reduced overall circulation, disrupted spring seasonality, and persistent impacts on high-risk pediatric populations. These findings provide evidence to optimize diagnostic testing for hMPV while providing actionable evidence to adjust optimal diagnostic testing windows, enhance infection prevention strategies, and implement focused monitoring of high-risk populations. Specifically, hMPV testing should be prioritized for pediatric patients during the typical peak months (March - May) and expanded to include atypical winter peaks (December - February) in the post-pandemic era. For older adults (≥ 65 years), targeted testing during winter months may enhance diagnostic yield and support timely clinical management.