The influenza virus hammering states in other parts of the country is slowly moving into Northern California, officials said Thursday.

The Influenza A (H3N2) strain currently predominating is causing more people to become severely ill and is increasing hospitalizations this season, local health officials and the U.S. Centers for Disease Control (CDC) said.

The more severe illness is typical with H3N2 viruses, and officials are predicting a "moderately severe" flu season, according to the CDC. But one concern is that the season has started earlier than usual this year. The flu season typically begins in February, but this year it started in early January in many states, according to the CDC.

So far 18 children have died due to complications from the disease. And the percentage of people nationwide seeing a doctor for flu-like illness is more than double last season's peak of 2.2 percent. In the past four weeks, the percentage has jumped sharply from 2.8 to 5.6 percent, according to the CDC, which tracks the flu's national progression and issues a weekly report.

Although 29 states have reported high levels of influenza-like illness, with another nine states reporting moderate levels, California has not yet seen many cases, according to Santa Clara County officials.

Dr. Cornelia Dekker, medical director of the Stanford-Lucile Packard Children's Hospital Vaccine Program, said so far only 15 confirmed cases of influenza have been reported by the Stanford lab, which tests suspected cases coming into Stanford's hospital, clinics and emergency room and for Lucile Packard Children's Hospital.

"We're nowhere near what the other states are experiencing, but I'm sure our time is coming," she said.

Dr. Joe Bresee, chief of the Epidemiology and Prevention Branch in the CDC's Influenza Division, said in a statement that the number of hospitalizations is also high for this time of year.

"While we can't say for certain how severe this season will be, we can say that a lot of people are getting sick with influenza. ... Anyone who has not already been vaccinated should do so now," he said.

Dekker said that flu sets its own pace, and although it does tend to go from east to west, no one can really predict which states will be hardest hit and if any will have fewer numbers of infections.

"Strains also mutate over time, so we're always dealing with a new set of characters," she said.

This year's flu started with Influenza B infections, but now the predominant strain is the Influenza A (H3N2), she said. The old pandemic H1N1 strain from 2009 is taking up much less space in the pantheon of flu viruses going around this year, she said.

Dekker said there is still time to get a flu shot. It takes about two weeks to build up antibodies for protection. Three strains of influenza are in the vaccine, which has only dead virus. "Fortunately, the vaccine choice was a good match for what we're seeing right now," she said.

Only about 50 percent of children and adults were immunized last year, she said. The more people who are vaccinated, the smaller the pool of potentially infected people will be out there spreading the germ, she said.

People who are concerned about vaccines containing preservative can obtain preservative-free flu shots, and now new microneedles are available for people ages 18 to 64 who fear injections, she said.

Another important new influenza vaccine offers a high dose for seniors that has four times as much antigen to give the elderly added protection, she said. The alternatives are available through many pharmacies and doctors, she said.
 

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