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This Web page is no longer being maintained or updated; it is provided for historical purposes only. For current information on seasonal influenza (flu), see the California Department of Public Health Influenza Web page.

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 H1N1 Flu Information

Related Information

H1N1 Flu Specific Patient Groups and Settings Information for Health Professionals

Most people who get the flu (either seasonal or 2009 H1N1) will have mild illness, will not need medical care or antiviral drugs, and will recover in less than two weeks.  Some people, however, are more likely to get flu complications that result in being hospitalized and occasionally result in death. Pneumonia, bronchitis, sinus infections and ear infections are examples of flu-related complications. The flu can also make chronic health problems worse. For example, people with asthma may experience asthma attacks while they have the flu, and people with chronic congestive heart failure may have worsening of this condition that is triggered by the flu.  The list below includes the groups of people more likely to get flu-related complications if they get sick from influenza.

What's New

  • CDPH Guidance: Considerations Regarding Management of 2009 H1N1 Influenza in the Postpartum Period in the Hospital and Home Setting (PDF)  - May 10, 2010
  • CDPH Guidance for Emergency Shelters for the 2009-2010 Flu Season (PDF) Opens in a new browser window. - December 7
  • Recommendations for Early Empiric Antiviral Treatment in Persons with Suspected Influenza who are at Increased Risk of Developing Severe Disease - CDC Health Alert Network (HAN), October 19
  • People at High Risk for Flu Complications:

  • Children younger than 5, but especially children younger than 2 years old
  • Adults 65 years of age and older
  • Pregnant women
  • People who have:
  • Cancer
  • Blood disorders (including sickle cell disease)
  • Chronic lung disease [such as asthma or chronic obstructive pulmonary disease (COPD)]
  • Diabetes
  • Heart disease
  • Kidney disorders
  • Liver disorders
  • Neurological disorders (such as epilepsy, cerebral palsy, brain or spinal cord injuries,  moderate to profound intellectual disability [mental retardation] or developmental delay)
  • Neuromuscular disorders (such as muscular dystrophy and multiple sclerosis)
  • Weakened immune systems (such as people with HIV or AIDS or who are on medications that weaken the immune system )
  • Clinician Guidance for Specific Patient Groups

    All CDPH Guidances for H1N1 Influenza - by Date and by Topic 

    CDC and Other Guidances for H1N1 Influenza - by Date and by Topic 


  • Adults

  • Pregnant Women

  • Asthma

  • Cardiovascular Disease

  • HIV-Infected Adults and Adolescents

  • Diabetes

  • Arthritis

  • Clinician Guidance for Specific Settings

    Last modified on: 8/25/2011 2:26 PM