One kind of germ is a virus. Viruses are so small that you can’t see them even with a normal microscope. But if you use a more powerful electron microscope, you’d see each one wears a kind of coat with bits and knobs that stick out in different directions.
“Just like every person’s face looks different, every virus coat looks different,” said my friend Felix Lankester, a veterinarian at Washington State University.
Read all of this answer from Dr. Universe at https://askdruniverse.wsu.edu/2016/12/05/vaccines-how-do-they-work/.
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