A 53-year-old engineer with diabetes mellitus comes to the employee health center for an annual examination. She has no complaints at this time. A review of her chart reveals that she is due for a few vaccinations, including the influenza A vaccine. She questions the physician about the necessity of the vaccine because she just received one a year ago. Which of the following statements about the influenza A virus best explains why last year's vaccine may be ineffective?

1. A)It has a heavy polysaccharide coat.
2. B)It kills lymphocytes.
3. C)It immunosuppresses the patient.
4. D)It resists inactivation by complement.
5. E)It undergoes genetic reassortment.GABARITO