On Thursday, health officials announced that flu shots are only 23 percent effective against this season's strain. This is not a good sign in a season where it seems more and more people are being stricken down with the flu. 

During normal flu seasons, the shot will prevent 60 percent to 65 percent of infections that are serious enough for people to seek medical attention.

This year's flu vaccines are less effective than usual, because the viruses used to make them aren't a good match for the viruses most people in the U.S. are being infected with, according to the Centers for Disease Control and Prevention.

However, the CDC still recommends that people get flu shots. Fewer than half of Americans have received the flu shot this year.