In this illustration, new viruses emerge from an infected human throat cell. When you get the flu, viruses turn your cells into tiny virus factories that help spread the disease. Courtesy XVIVO/Zirus hide caption

itoggle caption Courtesy XVIVO/Zirus

In this illustration, new viruses emerge from an infected human throat cell. When you get the flu, viruses turn your cells into tiny virus factories that help spread the disease. Courtesy XVIVO/Zirus hide caption

itoggle caption Courtesy XVIVO/Zirus