Establishing influenza epidemic thresholds and intensity levels in Türkiye using the moving epidemic method and assessing concordance with WHO transmission zones: A sentinel surveillance analysis of ten seasons, 2013–2025
- 1Department of Public Health, Division of Epidemiology, Ankara University School of Medicine, Ankara, Türkiye
- 2Department of Health Informatics, Graduate School of Informatics, Middle East Technical University, Ankara, Türkiye
Abstract
The Moving Epidemic Method (MEM) is the ECDC/WHO-Europe-endorsed approach for establishing influenza epidemic thresholds and intensity levels, yet no positivity-based MEM analysis exists for Türkiye or any country in the WHO Western Asia transmission zone. Weekly influenza positivity rates from FluNet sentinel surveillance were analysed for ten of twelve seasons (2013/2014–2024/2025, excluding two COVID-19 pandemic seasons) using the mem R package with cross-validated optimized slope parameter, and Türkiye’s average epidemic curve and thresholds were compared with the Western Asia (excluding Türkiye) and South West Europe zones using Lin’s concordance correlation coefficient (CCC), root mean square deviation (RMSD) and complementary correlation metrics. The epidemic threshold was 10.59% positivity, with intensity thresholds at 42.56% (medium), 60.92% (high), and 71.38% (very high); cross-validated sensitivity was 0.77, specificity 0.88, and Matthews correlation coefficient 0.65. Türkiye’s average curve showed higher concordance with Western Asia (CCC=0.890; RMSD=4.22 percentage points) than South West Europe (CCC=0.672; RMSD=12.48) despite similar Pearson correlations (0.922 vs. 0.939), and the Western Asia epidemic threshold (11.50%) closely matched Türkiye’s. These first operational MEM thresholds for Türkiye and the first positivity-based thresholds for the Western Asia zone confirm alignment with the current WHO transmission zone classification and support integration into routine surveillance.
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BibTeX
@article{ontas2026establishing,
title = {{Establishing influenza epidemic thresholds and intensity levels in Türkiye using the moving epidemic method and assessing concordance with WHO transmission zones: A sentinel surveillance analysis of ten seasons, 2013–2025}},
author = {Eray Ontas},
journal = {Epidemiology and Infection},
year = {2026},
month = oct,
doi = {10.1017/s095026882610209x},
url = {https://doi.org/10.1017/s095026882610209x},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Establishing influenza epidemic thresholds and intensity levels in Türkiye using the moving epidemic method and assessing concordance with WHO transmission zones: A sentinel surveillance analysis of ten seasons, 2013–2025
AU - Eray Ontas
PY - 2026
DA - 2026/10/15
JO - Epidemiology and Infection
DO - 10.1017/s095026882610209x
UR - https://doi.org/10.1017/s095026882610209x
AB - The Moving Epidemic Method (MEM) is the ECDC/WHO-Europe-endorsed approach for establishing influenza epidemic thresholds and intensity levels, yet no positivity-based MEM analysis exists for Türkiye or any country in the WHO Western Asia transmission zone. Weekly influenza positivity rates from FluNet sentinel surveillance were analysed for ten of twelve seasons (2013/2014–2024/2025, excluding two COVID-19 pandemic seasons) using the mem R package with cross-validated optimized slope parameter, and Türkiye’s average epidemic curve and thresholds were compared with the Western Asia (excluding Türkiye) and South West Europe zones using Lin’s concordance correlation coefficient (CCC), root mean square deviation (RMSD) and complementary correlation metrics. The epidemic threshold was 10.59% positivity, with intensity thresholds at 42.56% (medium), 60.92% (high), and 71.38% (very high); cross-validated sensitivity was 0.77, specificity 0.88, and Matthews correlation coefficient 0.65. Türkiye’s average curve showed higher concordance with Western Asia (CCC=0.890; RMSD=4.22 percentage points) than South West Europe (CCC=0.672; RMSD=12.48) despite similar Pearson correlations (0.922 vs. 0.939), and the Western Asia epidemic threshold (11.50%) closely matched Türkiye’s. These first operational MEM thresholds for Türkiye and the first positivity-based thresholds for the Western Asia zone confirm alignment with the current WHO transmission zone classification and support integration into routine surveillance.
SN - 0950-2688
SN - 1469-4409
ER -