The Nationwide flu outbreak is hitting Boston hard. So hard in fact that  Mayor Menino has declared a public health emergency.

Since October there have been 700 confirmed cases of influenza, a staggering statistic compared to last year's flu season, which yielded  70  cases.

So why is this year particularly fierce? Is the vaccine the best option we have to protect ourselves against the flu?  To answer these questions, among others, we spoke with Dr. William Hanage.

GUEST: Dr. William Hanage, Associate Professor of Epidemiology at the Harvard School of Public Health