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Volume 32, Supplement –Summer 2026

SUPPLEMENT ISSUE
Supplement

Early-Season Detection of Influenza A(H3N2) Subclade K in Wastewater, Colorado, USA, 2025–2026

Molly C. Hetherington-Rauth, Van Nguyen, Emily Washeleski, Kevin Castro Vital, Gabrielle Lequia, Deborah Aragon, Nisha B. Alden, Kirsten Weisbeck, Laura Bankers, Alexandria Rossheim, Allison Wheeler, and Shannon R. MatzingerComments to Author 
Author affiliation: Colorado Department of Public Health and Environment, Denver, Colorado, USA

Main Article

Figure 3

Wastewater sequencing metrics in study of early-season detection of influenza A(H3N2) subclade K in wastewater, Colorado, USA, 2025–2026. A) Percentage coverage of HA gene plotted against influenza A viral concentration. Orange represents sample with the first subclade K detection, collected October 16, 2025. Red represents samples with >60% coverage required for performing deconvolution. Gray represents samples with <60% coverage. Horizontal dashed line indicates the tiled amplicon scheme, which covers 86.7% of the HA gene reference sequence. Vertical dashed line indicates the defined limit of quantification, 1,200 gc/L. B) Percentage coverage of HA gene plotted against sample collection date. Horizontal dashed line indicates the tiled amplicon scheme, which covers 86.7% of the HA gene reference sequence. Vertical dashed line indicates the collection date of the first clinical sample characterized as subclade K, October 23, 2025. gc, gene copies; HA, hemagglutinin.

Figure 3. Wastewater sequencing metrics in study of early-season detection of influenza A(H3N2) subclade K in wastewater, Colorado, USA, 2025–2026. A) Percentage coverage of HA gene plotted against influenza A viral concentration. Orange represents sample with the first subclade K detection, collected October 16, 2025. Red represents samples with >60% coverage required for performing deconvolution. Gray represents samples with <60% coverage. Horizontal dashed line indicates the tiled amplicon scheme, which covers 86.7% of the HA gene reference sequence. Vertical dashed line indicates the defined limit of quantification, 1,200 gc/L. B) Percentage coverage of HA gene plotted against sample collection date. Horizontal dashed line indicates the tiled amplicon scheme, which covers 86.7% of the HA gene reference sequence. Vertical dashed line indicates the collection date of the first clinical sample characterized as subclade K, October 23, 2025. gc, gene copies; HA, hemagglutinin.

Main Article

Page created: June 29, 2026
Page updated: September 15, 2026
Page reviewed: September 15, 2026
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