Eli5: Why haven’t humans developed an immunity against the common cold?

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Eli5: Why haven’t humans developed an immunity against the common cold?

In: Biology

The common cold isn’t just one disease but a bucket of different strains and varieties. On top of that, all viruses and bacteria evolve and mutate incredibly fast, so last year’s cold might not have much in common with this year’s cold.

There is no such thing as the common cold. What we perceive as the common cold is really a collection of thousands of different strains of similar a virus that mutates quickly. You never catch the same strain twice, but there are more than enough for you to catch a new one every now and then.

When you get a cold, you develop an immunity that cold and possibly partial immunity to related strains. So every cold you get is a different disease. There are so many different strains of the cold virus that there is always a new cold you’re exposed to.