Why Is There No Lifelong Vaccine Protection Against Flu as There

question 3

Multiple Choice

Why is there no lifelong vaccine protection against flu as there is by a measles vaccine?

• A)The variety of flu strains is too great to be captured by a single vaccine.
• B)Flu can escape host immunity by evolving new variants that re-infect hosts.
• C)The flu is too virulent to effectively vaccinate against.
• D)The antigenic memory against flu has a short half-life.