Every year the flu vaccine is designed to protect against three different strains of the influenza virus.Why do scientists typically have to make a new vaccine every year?
A) because our bodies develop resistance to the vaccine and it becomes less effective
B) because the viruses develop resistance to the vaccine
C) because the viruses can mutate into new strains
D) because people change their habits each year and become susceptible to different strains of the virus
E) because a vaccine breaks down after one year

Question

Quizplus · Accepted Answer

The common flu each year can be a mix of strains, and each year new strains emerge.

Every Year the Flu Vaccine Is Designed to Protect Against