We applied inverse probability weighting to calculate age-adjusted estimates of the percentage of FNY participants in the United States who sought health care for ILI symptoms during the 2015-16 through 2018-19 influenza season and compared seasonal trends across different demographic and regional subgroups, including age group, sex, census region, and place of care using adjusted Chi-square tests.

The overall age-adjusted percentage of FNY participants who sought health care for ILI symptoms varied by season and ranged from 22.8% to 35.6%. Across all seasons, health care seeking was highest for the <18 and 65+ age groups, females had a greater percentage compared with males, and the South census region had the largest percentage while the West census region had the smallest percentage.

The percentage of FNY participants who sought health care for ILI symptoms varied by season, geographical region, age group, and sex. FNY compliments existing surveillance systems and informs estimates of influenza-associated illness by adding important real-time insights into health-care seeking behavior.

Flu Near You (FNY) is an online participatory syndromic surveillance system that collects health related information. In this manuscript, we summarized the health-care seeking behavior of FNY participants who reported influenza-like illness (ILI) symptoms.