Surveillance for Pediatric Deaths Associated with 2009 Pandemic Influenza A (H1N1) Virus Infection --- United States, April--August 2009

Surveillance for Pediatric Deaths Associated with 2009 Pandemic Influenza A (H1N1) Virus Infection --- United States, April--August 2009

Children aged <5 years or with certain chronic medical conditions are at increased risk for complications and death from influenza (1--3). Because of this increased risk, the Advisory Committee on Immunization Practices (ACIP) has prioritized influenza prevention and treatment for children aged <5 years and for those with certain chronic medical and immunosuppressive conditions (4,5). CDC monitors child influenza deaths through its influenza-associated pediatric mortality reporting system. As of August 8, 2009, CDC had received reports of 477 deaths associated with 2009 pandemic influenza A (H1N1) in the United States, including 36 deaths among children aged <18 years. To characterize these cases, CDC analyzed data from April to August 2009. The results of that analysis indicated that, of 36 children who died, seven (19%) were aged <5 years, and 24 (67%) had one or more of the high-risk medical conditions. Twenty-two (92%) of the 24 children with high-risk medical conditions had neurodevelopmental conditions. Among 23 children with culture or pathology results reported, laboratory-confirmed bacterial coinfections were identified in 10 (43%), including all six children who 1) were aged ≥5 years, 2) had no recognized high-risk condition, and 3) had culture or pathology results reported. Early diagnosis of influenza can enable prompt initiation of antiviral therapy for children who are at greater risk or severely ill. Clinicians also should be aware of the potential for severe bacterial coinfections among children diagnosed with influenza and treat accordingly. All children aged ≥6 months and caregivers of children aged <6 months should receive influenza A (H1N1) 2009 monovalent vaccine when available (6).

Influenza-associated pediatric deaths have been nationally notifiable since October 2004. The CDC case reporting system defines an influenza-associated pediatric death as a death in a person aged <18 years with an illness clinically compatible with influenza and whose influenza is laboratory confirmed. State and local health departments report influenza-associated pediatric deaths using a standardized case report form that collects information on demographics, dates of illness onset and death, location of death, chronic medical conditions, influenza testing, bacteria or fungi cultured from sterile and nonsterile sites, and medical care received during the influenza illness. The case report form provides a list of chronic medical conditions that have been associated previously with an increased risk for complications from seasonal influenza and space to describe additional chronic medical conditions not listed on the form. Results of pathology testing conducted at CDC also are included. Medical records, medical examiner reports, and death certificates were not reviewed.

This case series included data reported to CDC on all deaths associated with laboratory-confirmed 2009 pandemic influenza A (H1N1) virus infection occurring in persons aged <18 years through August 8, 2009. Laboratory confirmation was defined as a positive test for 2009 pandemic influenza A (H1N1) virus by reverse transcription--polymerase chain reaction (RT-PCR). CDC requested supplementary information from state and local health departments on antiviral treatment and chronic medical conditions for deaths associated with 2009 pandemic influenza A (H1N1) virus infection. For this case series, invasive bacterial coinfection was defined as laboratory detection of a bacterial pathogen in a specimen from a normally sterile site or a postmortem lung biopsy. Children were considered at high risk if they were aged <5 years or had one of the medical conditions recognized to increase the risk for influenza-related complications,* based on a review of the available medical data by a developmental pediatrician.

Thirty-six pediatric deaths associated with 2009 pandemic influenza A (H1N1) infection were reported from 15 state and local health authorities† through August 8 (Table 1).§ Illness onsets occurred during May 9--July 20, and deaths occurred during May 15--July 28. Six deaths occurred in May, 25 deaths in June, and five deaths in July. Median age of the patients was 9 years (range: 2 months--17 years); 50% were male, 42% were non-Hispanic white, and 33% were Hispanic (Table 2). Seven (19%) of the 36 children were aged <5 years (five were aged <2 years), and 24 (67%) had at least one high-risk medical condition, including three children aged <5 years. Among the 24 children with high-risk medical conditions, 22 (92%) had neurodevelopmental conditions (e.g., developmental delay or cerebral palsy). Of these 22 children, 13 (59%) had more than one neurodevelopmental diagnosis, and nine (41%) had neurodevelopmental and chronic pulmonary conditions. Eight (22%) of the 36 children were aged ≥5 years with no reported high-risk conditions. Two of these eight children were reported as obese; however, height and weight measurements were not reported.

Duration of illness before death in the 36 cases ranged from 1 day to 28 days (median: 6 days). Among 31 children for whom antiviral treatment data were available, 19 (61%) received antiviral treatment, and four of those received treatment within 2 days of illness onset. Of 25 children for whom information was available, 13 (52%) had received at least 1 dose of the 2008--09 seasonal influenza vaccine, including 11 children with high-risk medical conditions. Of the 23 children with culture or pathology results reported, 10 (43%) had a laboratory-confirmed bacterial coinfection, including Staphylococcus aureus (five, including three methicillin-resistant S. aureus), Streptococcus pneumoniae (three), Streptococcus pyogenes (one), and Streptococcus constellatus (one). Among the eight children aged ≥5 years who did not have a high-risk medical condition, six had a laboratory-confirmed invasive bacterial coinfection, including four with S. aureus; the other two children either had no specimens collected or information regarding bacterial coinfection was unavailable. Among the seven children aged <5 years who died, two had a laboratory-confirmed bacterial coinfection; neither child had a high-risk medical condition.

Reported by: S Shannon, MPH, Arizona Dept of Health Svcs. J Louie, MD, California Dept of Public Health. A Siniscalchi, MPH, Connecticut Dept of Public Health. E Rico, MPH, Miami-Dade County Health Dept, Florida. D Richter, Illinois Dept of Public Health. R Hernandez, MPH, Massachusetts Dept of Public Health. R Lynfield, MD, Minnesota Dept of Health. L McHugh, MPH, New Jersey Dept of Health and Senior Svcs. C Waters, New York State Dept of Health. E Lee, MD, A Stoute, MPH, New York City Dept of Health and Mental Hygiene. K Landers, MD, Marion County Health Dept, Oregon. U Bandy, MD, Rhode Island Dept of Health. N Pascoe, Texas Dept of State Health Svcs. V Vernon, MPH, Utah Dept of Health. T Haupt, MS, Wisconsin Dept of Health Svcs. C Moore, MD, L Schieve, PhD, G Peacock, MD, C Boyle, PhD, M Honein, PhD, M Yeargin-Allsopp, MD, E Trevathan, MD, National Center on Birth Defects and Developmental Disabilities; L Finelli, DrPH, T Uyeki, MD, R Dhara, MPH, A Fowlkes, MPH, Influenza Div, National Center for Immunization and Respiratory Diseases; D Christensen, PhD, V Jarquin, PhD, EIS officers, CDC.

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Surveillance for Pediatric Deaths Associated with 2009 Pandemic Influenza A (H1N1) Virus Infection --- United States, April--August 2009