H1N1 attributed to 9 child deaths in California after 2009 outbreak

Louie JK. Arch Pediatr Adolesc Med. 2010;164:1023-1031.

More than one-quarter of California children who were hospitalized with 2009 H1N1 required intensive care and/or died, according to a study conducted by the California Pandemic (H1N1) Working Group.

Between April 23 and Aug. 11, 2009, there were 1,090 incidents of hospitalization and death caused by H1N1 in California, of which 345 were in children aged younger than 18 years. Of the 345 children, 27% required intensive care and 3% died of 2009 H1N1, according to data reported to the California Department of Public Health.

The median time between symptom onset and hospitalization was 2 days. The most common symptoms were fever, cough, shortness of breath, nausea or vomiting, diarrhea and muscle aches. More than half of the patients had pneumonia. More than two-thirds received antiviral treatment.

Comorbid conditions that were considered Advisory Committee on Immunization Practices risk factors for severe influenza were present in 67% of the children, the most common being chronic pulmonary disease (including asthma), underlying neurological disorders (including cerebral palsy/developmental delay and seizure disorder) and immunosuppression. Non-ACIP risk factors such as gastrointestinal disorders and a history of prematurity were present in 28% of the children.

On multivariate analysis, congenital heart disease and cerebral palsy/development delay were associated with increased likelihood of ICU admission and/or death.

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