In the great scheme of things in the universe, we do have some things which help us against these tiny pests.
For one thing, we have some “built-in” protections of our own. Our skin, and the mucous membranes which are inside your body openings, are very effective in preventing viruses from getting right inside, you where they can get at your interior cells.
Then, when cells are injured by viruses, they often release substances which are antiviral in nature and white blood cells (which eat bacteria and other foreign materials) to get into your blood.