The influenza virus is extremely tiny. A human cell is the size of a small city to an influenza virus. Hundreds of thousands of influenza viruses can fit in a single human cell. Influenza virus: 100 nm wide Human bronchial epithelial cells: 10 μm wide E.coli: 0.6 μm * 3 μm An influenza virus is one millionth the size of the cells it infects.