Why are so many seniors dying of flu?

(CBS News) The U.S. Centers for Disease Control and Prevention says senior citizens are dying at the highest rate ever seen from the flu.

They're dying more often because this year's flu strain is "a bit more virulent" than previous years, according to Dr. William Schaffner, of Vanderbilt University, past president of the National Foundation for Infectious Diseases.

Seniors are often more susceptible to flu, according to Schaffner, because their immune systems are more frail than young, robust people. He said, "When flu strikes, they're more likely to get the complications of influenza."

But this year's strain is "more apt to cause serious disease," he said. "That's a nasty combination -- more virulent virus and seniors, of course, who are frail," Schaffner said. "So we're seeing complications, hospitalizations, and some deaths in seniors now."

Schaffner said serious flu comes every winter and suggested everyone get their flu shot every year in the fall. However, if you feel sick, Schaffner said you should call your health care provider to get a prescription anti-viral, such as Tamiflu, to reduce the duration and severity of the illness.

For more with Schaffner, watch the video in the player above.