Flu viruses in the throat. Computer artwork of influenza (flu) viruses (ovals) in a human throat. The lining of the throat includes cells that are covered in cilia (small hair-like projections). These cilia normally move rhythmically to help expel dust, micro-organisms and other particles. However, a large number of viruses in the throat can prevent the cilia from working properly, allowing the viruses to infect the cells of the throat and lungs.