Introduction: Evidence on the impact of influenza on health-related quality of life (HRQoL) and work productivity and activity impairment (WPAI) remains limited. This study evaluated changes in the EuroQol Visual Analogue Scale (EQ-VAS), EuroQol Utility Index (EQ-UI), absenteeism, presenteeism, work productivity loss, and activity impairment over 1 month during the high-severity 2024-2025 influenza season in the USA.

Methods: Symptomatic adults (≥ 18 years) with a positive influenza test at ambulatory care clinics within a national US retail pharmacy chain (10/24/2024-4/15/2025) and symptom onset ≤ 4 days of positive test were included. HRQoL was assessed on days 1-7, 10, 14, and week 4 and WPAI on days 1, 7, 14, and week 4. Mixed models for repeated measures estimated mean changes and standard error (SE) from baseline, adjusting for relevant covariates.

Results: The analysis included 724 adults (mean [standard deviation (SD)] age: 42.0 [13.0] years; 74.2% female). HRQoL declined following infection: EQ-VAS decreased by 26.6 points (SE 0.9) on day 1 (p < 0.001) and 3.8 (0.8) on day 10 (p < 0.001), while EQ-UI scores decreased by 0.20 (0.01) on day 1 (p < 0.001) and 0.02 (0.01) on day 7 (p < 0.001). Compared with baseline, absenteeism rose by 58.3% (1.9) on day 1 and 34.9% (1.9) on day 7 (p < 0.001); presenteeism increased by 59.2% (2.0), 43.2% (2.0), and 8.8% (1.7) on days 1, 7, and 14 respectively (p < 0.001). Work productivity loss rose by 76.3% (1.7) on day 1, 55.5% (2.1) on day 7, and 8.1% (1.8) on day 14 (p < 0.001). Activity impairment increased by 62.6% (1.6) on Day 1, 43.6% (1.8) on day 7, and 6.6% (1.6) on day 14 (p < 0.001).

Conclusions: Influenza was associated with marked declines in HRQoL, productivity, and daily functioning in symptomatic outpatients, highlighting the importance of patient-reported outcomes in capturing influenza´s real-world burden.