Epidemiology of influenza A (H1N1)pdm09-associated deaths in the United States, September-October 2009.
BACKGROUND
From April to July 2009, the United States experienced a wave of influenza A (H1N1)pdm09 virus (H1N1pdm09) infection. The majority of the deaths during that period occurred in persons <65 years of age with underlying medical conditions.


OBJECTIVE
To describe the epidemiology of H1N1pdm09-associated deaths in the US during the fall of 2009.


METHODS
We collected demographic, medical history, and cause of death information on a nationally representative, stratified random sample of 323 H1N1pdm09-associated deaths that occurred during September 1-October 31, 2009.


RESULTS
Data were available for 302/323 (93%) deaths. Most cases (74%) were 18-64 years of age and had ≥ 1 underlying medical condition (72%). Among cases aged <18 years, 16/43 (37%) had a chronic lung disease, and 15/43 (35%) a neurological disorder; among cases aged ≥ 18 years, 94/254 (37%) had a chronic lung disease and 84/254 (33%) had a metabolic disorder. The median number of days between symptom onset and death was six among children (range, 1-48) and 12 among adults (range, 0-109). Influenza antiviral agents were prescribed for 187/268 (70%) of cases, but only 48/153 (31%) received treatment within 2 days of illness onset.


CONCLUSIONS
The characteristics of H1N1pdm09 deaths identified during the fall of 2009 were similar to those occurring April-July 2009. While most cases had conditions that were known to increase the risk for severe outcomes and were recommended to receive antiviral therapy, a minority of cases received antivirals early in the course of illness.
National Center for Emerging Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
Joanna
J
Regan
Ashley
A
Fowlkes
Matthew
M
Biggerstaff
Michael A
MA
Jhung
Jacqueline
J
Gindler
Erin
E
Kennedy
Victoria
V
Fields
Lyn
L
Finelli
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000998:Antiviral Agents / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification* / Q000472:pathogenicity; D007251:Influenza, Human / Q000188:drug therapy / Q000453:epidemiology* / Q000401:mortality* / Q000821:virology; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D016019:Survival Analysis; D013997:Time Factors; D014481:United States / Q000453:epidemiology; D055815:Young Adult
D000998:Antiviral Agents