Which of the following is the most likely reason that we need to develop a new flu vaccine every year?
A) The flu virus evolves due to negative selection.
B) The flu virus evolves due to positive selection.
C) The vaccine evolves due to negative selection.
D) Humans evolve from year to year.
E) Our immune system degrades over time.

Question

Quizplus · Accepted Answer

The flu virus evolves due to positive selection, meaning that it undergoes genetic changes that allow it to better evade the immune system and continue to infect people. This is why a new flu vaccine must be developed each year to target the specific strains that are predicted to be most prevalent.

Which of the Following Is the Most Likely Reason That