Question

What happens to the influenza virus every 20-40 years, and why? What are the recent example(s)?

Answer 1

Answer:

The influenza virus is mutated every 20-40 years.

Explanation:

Large mutations occur every 20-40 years. This results in a new influenza virus to  which the human population has no protection. These large mutations are almost always followed by an influenza pandemic.

Hope this helps!