In light of an alarming spike in serious influenza infections among the young, the Kern County Public Health Services Department is reminding people that it's not too late to get a flu shot.

At least a dozen people have been hospitalized for the flu in Kern County since Friday.

"We know it's flu season and people are going to get it," said Dr. Claudia Jonah, Kern County health officer. "What concerns us is the sudden increase in serious cases, and the age of the people getting so sick that they need to be hospitalized."

Typically, severe cases of the flu are seen in children, the elderly and people with underlying medical conditions.

The spat of local reported cases involved patients ranging in age from 30 to 68 years old. It's unusual to see so many serious cases among young adults in such a short period of time, Jonah said.

What's happening locally mirrors a national trend.

Last week, the number of people across the country seeking medical help for flu-like symptoms was up for the fourth consecutive week, according to the Centers for Disease Control and Prevention.

There have been 1,156 laboratory-confirmed flu-related hospitalizations nationwide since Oct. 1, according to the CDC.

A lot of them were young and middle-aged people with the H1N1 strain of the flu. That strain hits young, healthy people the hardest, and was the cause of a worldwide pandemic alert in 2009.

That year, the flu caused more illness in children and young adults than in older adults.

Of the 12 adults hospitalized with the flu in Kern County since Friday, eight were infected with the H1N1 strain, Jonah said.

Only one of them had had a flu shot.

The seasonal flu shot contains three influenza viruses -- one influenza A (H3N2) virus, one seasonal influenza A (H1N1) virus, and one influenza B virus.

The precise design of the vaccine is tweaked every year to protect against the strains forecast to cause the most illness in the coming season.

Flu season ramps up in September and usually peaks in January or February. The flu kills thousands of people every year, most often the elderly.

There are still shots available for the 2013-14 season. The shots are offered at the Kern County Public Health office and at many pharmacies.