2009 H1N1 Hospitalizations in People with Asthma

November 4, 2009

What does CDC know about hospitalizations among people with asthma who get 2009 H1N1 flu?
People with asthma are at higher risk for serious complications from influenza (flu), including 2009 H1N1 flu. This can place people with asthma at higher risk of hospitalization when they have 2009 H1N1 flu. CDC monitors 2009-H1N1 related hospitalizations, including among people with asthma, through the Emerging Infections Program (EIP).

What is the Emerging Infections Program (EIP)?
The EIP Influenza Project conducts surveillance for laboratory-confirmed influenza (flu) related hospitalizations in children (persons younger than 18 years) and adults in 62 counties covering 13 metropolitan areas of 10 states (for more information see the overview of influenza surveillance in the United States). Cases are identified by reviewing hospital laboratory and admission databases and infection control logs for children and adults with a documented positive influenza test* conducted as a part of routine patient care. EIP estimated hospitalization rates are reported every week during the flu season.

*Tests used by EIP to confirm influenza infection include viral culture, direct/indirect fluorescent antibody assay (DFA/IFA), real-time reverse transcriptase polymerase chain reaction (rRT-PCR), or a commercial rapid antigen test.

What percentage of people hospitalized with 2009 H1N1 flu have asthma?
According to Emerging Infections Program (EIP) data collected from April 15 through October 27, 2009, 32% of people hospitalized with 2009 H1N1 had asthma. Among adults hospitalized with 2009 H1N1, 30% had asthma, whereas 35% of hospitalized children with 2009 H1N1 had asthma.

What percentage of people hospitalized with asthma and 2009 H1N1 are admitted to an Intensive Care Unit (ICU)?
According to Emerging Infections Program (EIP) data collected from April 15 - October 27, 2009, 21% of hospitalized adults with asthma and a 2009 H1N1 infection and 18% of hospitalized children with asthma and a 2009 H1N1 infection were admitted to an ICU. No significant differences in the number of ICU admissions were noted between 2009 H1N1 infected people hospitalized with or without asthma.

2009 H1N1 Hospitalizations by Age Group

October 20, 2009

What percentage of hospitalizations for 2009 H1N1 flu occur in different age groups in the United States?

The percentage of hospitalizations for 2009 H1N1 flu in the United States varies by age group. From August 30, 2009 through October 10, 2009, states reported 4,958 laboratory-confirmed 2009 H1N1 hospitalizations to CDC. The percentage of 2009 H1N1 related hospitalizations that occurred among those 0 to 4 years old was 19%; among those 5 years to 18 years was 25%; among people 19 years to 24 years was 9%; among those 25 years to 49 years was 24%; among people 50 to 64 years was 15%; and among people 65 years and older was 7%. For a graphical representation of this data, please see the chart below.

What percentage of deaths for 2009 H1N1 flu occur in different age groups in the United States?

The percentage of deaths for 2009 H1N1 flu in the United States varies by age group. From August 30, 2009 through October 10, 2009, states reported 292 laboratory-confirmed 2009 H1N1 deaths to CDC. The percentage of 2009 H1N1 related deaths that occurred among people 0 years to 4 years was 3%; among those 5 years to 18 years was 14%; among people 19 to 24 years was 7%; among people 25 to 49 years was 33%; among people 50-64 years was 32%; and among people 65 years and older was 12%. For a graphical representation of this data, please see the chart below.