Question

if memory cells are always present after the first exposure to a virus, then why do people get the flu every year?

Answer 1

The flu virus mutates ever year and develops a new strain. This is why we all must get the flu vaccine every season because it keeps changing to the genetic makeup of the ever changing virus.

Answer 2

People get the flu every year because unfortunately the flu virus mutates every year.

Step-by-step explanation: