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California reports 45 flu deaths as H1N1 predominates nationally

The number of influenza-related deaths in California have increased by seven during the past week, according to the California Department of Public Health (CDPH) in a press release Jan. 17.

H1N1 influenza predominates this 2013-2014 flu season
H1N1 influenza predominates this 2013-2014 flu season
CDC

According to Dr. Ron Chapman, director of the California Department of Public Health (CDPH) and state health officer, the confirmed flu-related deaths in the state has increased to 45 for the season so far, including two pediatric deaths.

In addition, there are an additional 50 deaths under investigation, according to health authorities.

Chapman, like other health officials at all levels, reiterated to the public to get their flu shot. “Flu activity continues to increase statewide, including reports of hospitalizations, severe disease and the number of deaths,” said Dr. Chapman. “We are clearly in the midst of what appears to be an earlier peaking, severe flu season, and I encourage everyone who has not yet gotten a flu vaccination to do so. The influenza vaccine remains the most effective way to protect yourself from the flu.”

Related story: Misperceptions about flu vaccine concern health advocates

Flu-related deaths have been reported from 20 California counties to date.

Nationally, the Centers for Disease Control and Prevention (CDC) says there is now 40 states reporting "widespread" influenza activity, this is up from 35 states just one week ago.

The CDC says that while influenza A (H3N2), 2009 influenza A (H1N1), and influenza B viruses have all been identified in the U.S. this season. To date, influenza A (H1N1) viruses have predominated.

This is the H1N1 virus that emerged in 2009 to cause a pandemic. H1N1 viruses have continued to circulate among people since that time, but this is the first season that the virus has circulated at high levels since the pandemic.

While the greatest burden of hospitalizations and deaths usually occurs among people 65 and older, so far this season just 23 percent of hospitalizations have been in people 65 years and older.

This season’s pattern of more hospitalizations across younger age groups is likely due to existing levels of immunity to this virus across the population.

The CDC states:

Serology studies during the pandemic suggested that people 65 years or older had existing antibodies against H1N1 viruses, perhaps because they were exposed to similar viruses – predecessors of 2009 H1N1 viruses – earlier in their lifetimes.

The 2009 H1N1 virus is estimated to have caused 60.8 million illnesses among the more than 300,000,000 people in the United States over the course of the pandemic. So while some young people likely developed antibodies for H1N1, many probably did not.

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