Question

About a hundred years ago, when small pox persisted a group of people had this

disease earlier and had survived it, it had no chance of suffering from it again. So

having the disease once was means of preventing subsequent attacks of same disease.

I) Why does this happen. Explain

II).We can “fool” the immune system. Clarify

III) Name this principle of prevention of diseases.
Explain with Brief Explanation​

Answer 1

Explanation:

In other words, if you had smallpox once, there was no chance of suffering from it again. So, having the disease once was a means of preventing subsequent attacks of the same disease. This happens because when the immune system first sees an infectious microbe, it responds against it and then remembers it specifically.

Answer 2

Answer:

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