Question

Influenza occurs on an annual basis in the United States, with case counts generally peaking during the colder months of the year. In 2011, the approximate influenza case count in the US was 9,000,000. The population of the US in 2011 was approximately 300,000,000.

It is estimated that 30% of the US population either was immunized with vaccine or possessed natural immunity to 2011's flu strain.

Nearly 45,000 people died from influenza in the US during 2011's "flu season." The total number of deaths in the US that year from all causes was 3,000,000.

What was the case fatality rate (CFR) for influenza in 2011?

a) 50%

b) 5.0%

c) 0.5%

d) 0.05%

e) 55

Answer 1