Flu vaccine this season may be poorly matched, early CDC data suggests

This season's influenza vaccine may have been a poor match to a strain of the flu virus that caused many infections this winter, early data released by the Centers for Disease Control and Prevention suggests.

The CDC's latest data come as much of the U.S. is finally seeing signs of a slowdown in influenza activity after waves of illness this past fall and winter that climbed to the worst rates recorded from hospitals and doctor's offices since the 2009 swine flu pandemic.

"This is a bad year, no doubt about it," Dr. Jon LaPook, CBS News chief medical correspondent, told "CBS Mornings" on Tuesday.