Influenza type a viruses can cause severe illness and are responsible for influenze human pandemics. What is one evolutionary mechanism that could explain why we need a new influenza a virus vaccine every year?

Depends on which disease, but as a general rule eat healthy. many vegetables.                                                        hope my answer has come to your . you for posting your question here in we hope to answer more of your questions and inquiries soon. have a nice day ahead! : )     (p.s mark as brainliest if )