Using nationally representative micro panel data on flu incidence from the Medical Expenditure Panel Survey in the United States, we show that employed individuals are on average 35.3% more likely to be infected with the virus. Wage earners are more likely to be infected than the unemployed by 30.1% and than individuals out of the labor force by 40.8%. Our results are robust to individual characteristics including vaccinations, health insurance and unobserved heterogeneity. Within the employed, we find an occupation-flu gradient—e.g. sales occupations show 34.1% higher probability of infection than farmers. As a potential mechanism behind this gradient, we study occupation-specific exposure to human contact interaction at work—a score that we construct based on O’NET occupational characteristics—which, as we show, determines flu incidence. All these effects increase with the aggregate flu incidence and are robust to firm size and across industries.