The flu is deadly serious this year. How serious? On Wednesday, Boston declared a public health emergency after more than a dozen people there have been killed by the virus.

The emergency was declared in Boston after more than 700 people were reported with the flu, up 10 times from last year when there were just 70. To try to halt the spread of the virus, the city is offering free flu vaccines, but some doctors have noted that the vaccine doesn't protect against all strains of the bug that are out there. In all of Massachusetts, 18 people have died from the virus.

And Massachusetts is not alone. Montana, South Dakota and Arizona are now reporting that the virus is widespread, bringing the total to 44 states seriously affected by the flu.