Report: Drugmakers see shortage of flu shots

Influenza has swept the United States in the last month, arriving nearly five weeks earlier than usual.

As of the last week in December, the Centers for Disease Control and Prevention (CDC) reported that 41 states are experiencing "widespread geographic influenza activity," a sharp increase from the week before.

The share of people seeing doctors for flu-like symptoms recently hit 5.6 percent nationally, more than double the peak proportion from last year, the CDC said.