title: 2009 pandemic influenza A (H1N1) virus infections - Chicago, Illinois, April-July 2009.
abstract: On April 21, 2009, CDC reported the first cases of 2009 pandemic influenza A (H1N1) virus infection in the United States. On April 24, in response to those reports, the Chicago Department of Public Health (CDPH) established enhanced surveillance for 2009 pandemic influenza A (H1N1) virus infections. The first cases were identified on April 28. This report summarizes laboratory-confirmed cases identified during April 24-July 25 and provides clinical and epidemiologic data for a subset of those cases. By July 25, a total of 1,557 laboratory-confirmed cases had been reported to CDPH. The overall attack rate was highest among children aged 5-14 years (147 per 100,000 population), which was 14 times higher than for adults aged >or=60 years. A total of 205 (13%) patients were hospitalized, with the highest rate observed among children aged 0-4 years (25 per 100,000), followed by children aged 5-14 years (11 per 100,000). These findings affirm prevention strategies that target children and young adults, who are at a disproportionate risk for infection and hospitalization. The Advisory Committee on Immunization Practices (ACIP) recommends that these populations should be among the first groups targeted for vaccination with influenza A (H1N1) 2009 monovalent vaccine.
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002641:Chicago / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D053118:Influenza A Virus, H1N1 Subtype; D007252:Influenza Vaccines / Q000008:administration & dosage*; D007251:Influenza, Human / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D011247:Pregnancy; D012306:Risk; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines