California sees early flu spike as health officials urge residents to get vaccinated

Experts say they are tracking significant flu activity nationwide, while an early spike in California has health officials on high alert.

Dr. Dean Blumberg, chief of Pediatric Infectious Diseases at UC Davis Health, said it appears the entire country will experience an early flu season.

The flu season typically begins in early November, with activity generally peaking between January and March.  

Currently, the San Francisco Bay Area is categorized as having high circulation of influenza, whereas activity in the Sacramento region is categorized as moderate to high, according to data from the California Department of Public Health.

"Influenza has a sudden onset, very high fever, muscle aches, etc., and is usually more severe," Blumberg said.

Blumberg said he's seen the uptick firsthand and noted that the illness is mostly impacting kids born after 2009.

"It appears to be hitting younger people a little bit harder," he said.

Dr. Phoung Luu, Sacramento County's public health director, has been tracking this year's flu closely and said there have been "more [emergency department] visits throughout the state" this season.

More than 95% of cases have been identified by health officials as the Influenza A H1N1 strain.

"Throughout the state, there have already been 34 deaths related to flu," Luu said.

Health officials are urging Californians to get their flu shots.

"It takes one to two weeks to develop that immunity, so as rates are increasing, now is a good time to get vaccinated," Blumberg said.

CBS News Sacramento asked the county health department about the effectiveness of this year's flu vaccine. Health officials said it's hard to tell how well the vaccine will work until later in the season but noted that the current vaccines do protect against the H1N1 strain.