The answer might surprise you, it's because of the flu vaccine and the most recent research from the National Academy of Sciences proves that people who are vaccinated spread the virus more, are not protected, and prior vaccination is harming people's immunity!
Does the flu vaccine protect you or those around you? Well according to the research, the opposite would be true. The findings of the study found that those individuals who had received the flu vaccine were "shedding" 6.3 times more virus than the unvaccinated!
Straight from the research:
"Self-reported vaccination for the current season was associated with a trend (P < 0.10) toward higher viral shedding in fine aerosol samples; vaccination with both the current and previous year's seasonal vaccines, however, was significantly associated with greater fine-aerosol shedding in unadjusted and adjusted models (P < 0.01). In adjusted models, we observed 6.3 (95% CI 1.9–21.5) times more aerosol shedding among cases with vaccination in the current and previous season compared with having no vaccination in those two seasons."