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Influenza (sometimes called flu) is a contagious virus that can infect the nose, throat and sometimes the lungs.  It can cause mild to severe illness, and sometimes even death.  Although influenza affects all ages, it is most commonly spread among young children, and from them infects their household and other contacts, affecting the whole community.  It can be especially severe for those with certain chronic medical conditions (such as asthma, diabetes, or heart disease) or weakened immune systems, and for young children (<5 years of age), pregnant women, or people 65 years of age or older.  Influenza viruses are constantly changing so people can get infected with influenza every year.   The best way to prevent influenza is through annual vaccination.

The following types of influenza infections are reportable in Orange County:

  • Laboratory confirmed cases 0-64 years of age who are admitted to an intensive care unit (ICU); OR
  • Laboratory confirmed cases 0-64 years of age who have died; OR
  • Novel strains of influenza (including suspect human cases of avian influenza, variant influenza, or pandemic influenza); OR
  • Cases associated with an outbreak.

Any suspected novel influenza cases or outbreaks of influenza or influenza-like illness should be reported immediately by phone (714-834-8180) to OCHCA Epidemiology. Healthcare providers, hospitals and laboratories may be asked to submit additional reports or specimens as part of influenza surveillance or enhanced surveillance for novel strains.

Latest News


County of Orange Reports First Influenza-Related Death of Season
January 17, 2019
The Orange County Health Care Agency has confirmed Orange County's first influenza-related death in a person under 65 years of age this season.

Eye on Influenza 2018-19 Volume 15 Issue 4
January 16, 2019
Locally, influenza activity has significantly increased in recent weeks.

Healthcare Professionals

We are actively recruiting physicians and other health care providers to participate as sentinel providers for influenza surveillance. For more information about becoming a sentinel provider, or if you wish to receive our Eye on Influenza newsletter, please contact us

Additional Information 

Page Last Updated: February 5, 2019