2023
Bacterial and viral infections among adults hospitalized with COVID‐19, COVID‐NET, 14 states, March 2020–April 2022
Shah M, Patel K, Milucky J, Taylor C, Reingold A, Armistead I, Meek J, Anderson E, Weigel A, Reeg L, Como‐Sabetti K, Ropp S, Muse A, Bushey S, Shiltz E, Sutton M, Talbot H, Chatelain R, Havers F, Team T. Bacterial and viral infections among adults hospitalized with COVID‐19, COVID‐NET, 14 states, March 2020–April 2022. Influenza And Other Respiratory Viruses 2023, 17: e13107. PMID: 36875205, PMCID: PMC9981874, DOI: 10.1111/irv.13107.Peer-Reviewed Original ResearchMeSH KeywordsAdultBacterial InfectionsCoinfectionCOVID-19HumansInfluenza, HumanSARS-CoV-2Virus DiseasesConceptsDay of admissionSARS-CoV-2 infectionHospitalized adultsViral infectionBacterial coinfectionCOVID-19Laboratory-confirmed SARS-CoV-2 infectionBacterial infectionsPopulation-based surveillance systemRhinovirus/enterovirusRespiratory syncytial virusBacterial pathogensCoV-2 virusClinical featuresClinical outcomesViral coinfectionSyncytial virusHuman metapneumovirusParainfluenza virusRisk factorsSterile sitesEndemic coronavirusesRelative riskRelevant bacterial pathogensGram-negative rods
2022
Drug use and severe outcomes among adults hospitalized with influenza, 2016–2019
Parisi C, Yousey‐Hindes K, Holstein R, O'Halloran A, Kirley P, Alden N, Anderson E, Kim S, McMahon M, Khanlian S, Spina N, Gaitan M, Shiltz E, Thomas A, Schaffner W, Talbot K, Crossland M, Cook R, Garg S, Meek J, Hadler J. Drug use and severe outcomes among adults hospitalized with influenza, 2016–2019. Influenza And Other Respiratory Viruses 2022, 17: e13052. PMID: 36300969, PMCID: PMC9835414, DOI: 10.1111/irv.13052.Peer-Reviewed Original ResearchMeSH KeywordsAdultAsthmaFemaleHospitalizationHumansInfluenza, HumanIntensive Care UnitsMaleMorbidityConceptsSevere outcomesDrug useICU admissionMechanical ventilationInfluenza Hospitalization Surveillance NetworkInfluenza-associated outcomesSevere influenza outcomesPersistent public health problemChronic liver diseaseChronic lung diseasePublic health problemNon-Hispanic blacksLogistic regression modelsHispanics/LatinosSmoke tobaccoInfluenza vaccinationOpioid useImmunosuppressive conditionsInfluenza seasonSevere morbidityInfluenza infectionInfluenza outcomesLiver diseaseLung diseaseChronic conditions
2021
Hospital-acquired influenza in the United States, FluSurv-NET, 2011–2012 through 2018–2019
Cummings C, O’Halloran A, Azenkot T, Reingold A, Alden N, Meek J, Anderson E, Ryan P, Kim S, McMahon M, McMullen C, Spina N, Bennett N, Billing L, Thomas A, Schaffner W, Talbot H, George A, Reed C, Garg S. Hospital-acquired influenza in the United States, FluSurv-NET, 2011–2012 through 2018–2019. Infection Control And Hospital Epidemiology 2021, 43: 1447-1453. PMID: 34607624, DOI: 10.1017/ice.2021.392.Peer-Reviewed Original ResearchMeSH KeywordsAdultAgedChildCross-Sectional StudiesHospitalizationHospitalsHumansInfluenza VaccinesInfluenza, HumanSeasonsUnited StatesVaccinationConceptsHospital-acquired influenzaInfluenza-associated hospitalizationsHA influenzaHospital infection control measuresInfluenza Hospitalization Surveillance NetworkFacility-based testingPositive test dateRespiratory symptom onsetAnnual influenza vaccinationHA casesInfection control measuresSymptom onset dateCross-sectional studyYears of agePopulation-based ratesInfluenza vaccinationClinical characteristicsICU careSymptom onsetInfluenza vaccineMechanical ventilationSevere outcomesPatient outcomesInfluenza casesHospitalization
2016
Increased Antiviral Treatment Among Hospitalized Children and Adults With Laboratory-Confirmed Influenza, 2010–2015
Appiah GD, Chaves SS, Kirley PD, Miller L, Meek J, Anderson E, Oni O, Ryan P, Eckel S, Lynfield R, Bargsten M, Zansky SM, Bennett N, Lung K, McDonald-Hamm C, Thomas A, Brady D, Lindegren ML, Schaffner W, Hill M, Garg S, Fry AM, Campbell AP. Increased Antiviral Treatment Among Hospitalized Children and Adults With Laboratory-Confirmed Influenza, 2010–2015. Clinical Infectious Diseases 2016, 64: 364-367. PMID: 28013261, PMCID: PMC5480237, DOI: 10.1093/cid/ciw745.Peer-Reviewed Original ResearchMeSH KeywordsAdolescentAdultAgedAntiviral AgentsChildChild, PreschoolCohort StudiesFemaleHumansInfantInfant, NewbornInfluenza A Virus, H1N1 SubtypeInfluenza, HumanLength of StayLongitudinal StudiesMaleMiddle AgedOseltamivirPandemicsProspective StudiesRetrospective StudiesSeasonsUnited StatesYoung AdultCase-Control Study of Vaccine Effectiveness in Preventing Laboratory-Confirmed Influenza Hospitalizations in Older Adults, United States, 2010–2011
Havers F, Sokolow L, Shay D, Farley M, Monroe M, Meek J, Kirley P, Bennett N, Morin C, Aragon D, Thomas A, Schaffner W, Zansky S, Baumbach J, Ferdinands J, Fry A. Case-Control Study of Vaccine Effectiveness in Preventing Laboratory-Confirmed Influenza Hospitalizations in Older Adults, United States, 2010–2011. Clinical Infectious Diseases 2016, 63: 1304-1311. PMID: 27486114, DOI: 10.1093/cid/ciw512.Peer-Reviewed Original ResearchConceptsLaboratory-confirmed influenza hospitalizationsCase-control studyInfluenza hospitalizationsCase patientsAge groupsRecent hospitalizationRespiratory conditionsLower functional status scoresOlder adultsConditional logistic regression modelsAdjusted VE estimatesInfluenza-associated complicationsVaccine effectiveness dataChronic medical conditionsFunctional status scoresMonths of hospitalizationChronic health conditionsLogistic regression modelsPreventing LaboratoryInfluenza vaccinationVaccination statusVaccine effectivenessInfluenza seasonVE estimatesInfluenza infectionBenefit of Early Initiation of Influenza Antiviral Treatment to Pregnant Women Hospitalized With Laboratory-Confirmed Influenza
Oboho I, Reed C, Gargiullo P, Leon M, Aragon D, Meek J, Anderson E, Ryan P, Lynfield R, Morin C, Bargsten M, Zansky S, Fowler B, Thomas A, Lindegren M, Schaffner W, Risk I, Finelli L, Chaves S. Benefit of Early Initiation of Influenza Antiviral Treatment to Pregnant Women Hospitalized With Laboratory-Confirmed Influenza. The Journal Of Infectious Diseases 2016, 214: 507-515. PMID: 26908745, DOI: 10.1093/infdis/jiw033.Peer-Reviewed Original ResearchConceptsInfluenza antiviral treatmentSevere influenzaAntiviral treatmentLength of stayPregnant womenEarly initiationInfluenza vaccinationIntensive care unit admissionAnnual influenza vaccinationCare unit admissionLaboratory-confirmed influenzaUnit admissionPregnancy trimesterPreterm deliveryRespiratory failurePulmonary embolismInfluenza seasonMedian ageSeverity strataMechanical ventilationParametric survival analysisIllness onsetInfant morbidityMedian lengthFetal lossSurvey of influenza and other respiratory viruses diagnostic testing in US hospitals, 2012–2013
Su S, Fry AM, Kirley PD, Aragon D, Yousey‐Hindes K, Meek J, Openo K, Oni O, Sharangpani R, Morin C, Hollick G, Lung K, Laidler M, Lindegren ML, Schaffner W, Atkinson A, Chaves SS. Survey of influenza and other respiratory viruses diagnostic testing in US hospitals, 2012–2013. Influenza And Other Respiratory Viruses 2016, 10: 86-90. PMID: 26505742, PMCID: PMC4746564, DOI: 10.1111/irv.12355.Peer-Reviewed Original ResearchConceptsInfluenza Hospitalization Surveillance NetworkRespiratory virusesAvailable rapid influenza diagnostic testsRapid influenza diagnostic testsInfluenza diagnostic testsOptimal clinical managementInfection control practitionersSurvey of hospitalsDetection of influenzaSurveillance networkInfluenza infectionClinical managementCatchment populationStandardized questionnaireUS hospitalsHospitalDiagnostic testingInfluenzaLaboratory capacityTelephone interviewsDiagnostic testsMolecular diagnostic assaysInsensitive assayControl practitionersDiagnostic practice
2015
Impact of Prompt Influenza Antiviral Treatment on Extended Care Needs After Influenza Hospitalization Among Community-Dwelling Older Adults
Chaves S, Pérez A, Miller L, Bennett N, Bandyopadhyay A, Farley M, Fowler B, Hancock E, Kirley P, Lynfield R, Ryan P, Morin C, Schaffner W, Sharangpani R, Lindegren M, Tengelsen L, Thomas A, Hill M, Bradley K, Oni O, Meek J, Zansky S, Widdowson M, Finelli L. Impact of Prompt Influenza Antiviral Treatment on Extended Care Needs After Influenza Hospitalization Among Community-Dwelling Older Adults. Clinical Infectious Diseases 2015, 61: 1807-1814. PMID: 26334053, DOI: 10.1093/cid/civ733.Peer-Reviewed Original ResearchConceptsIllness onsetCommunity-dwelling adultsAntiviral treatmentExtended careCare needsEarly treatmentInfluenza hospitalizationsHospital dischargeIntensive care unit admissionLaboratory-confirmed influenza hospitalizationsOlder adultsCommunity-dwelling older adultsInfluenza antiviral treatmentPrompt antiviral treatmentCare unit admissionImpact of influenzaLength of stayRisk survival analysisUnit admissionHospital lengthInfluenza seasonShortens hospitalizationNeurologic disordersRehabilitation facilityAntiviral agentsImproving Accuracy of Influenza-Associated Hospitalization Rate Estimates - Volume 21, Number 9—September 2015 - Emerging Infectious Diseases journal - CDC
Millman A, Reed C, Kirley P, Aragon D, Meek J, Farley M, Ryan P, Collins J, Lynfield R, Baumbach J, Zansky S, Bennett N, Fowler B, Thomas A, Lindegren M, Atkinson A, Finelli L, Chaves S. Improving Accuracy of Influenza-Associated Hospitalization Rate Estimates - Volume 21, Number 9—September 2015 - Emerging Infectious Diseases journal - CDC. Emerging Infectious Diseases 2015, 21: 1595-1601. PMID: 26292017, PMCID: PMC4550134, DOI: 10.3201/eid2109.141665.Peer-Reviewed Original ResearchConceptsYears of ageHospitalization ratesAdults 18Test sensitivityLaboratory-confirmed influenza-associated hospitalizationsNational population-based surveillance systemLaboratory-confirmed influenza hospitalizationsPopulation-based surveillance systemInfectious Diseases journal - CDCInfluenza-associated hospitalizationsDiagnostic test typeFluSurv-NETInfluenza hospitalizationsInfluenza seasonPatient ageAge groupsTranscription-PCRAgeHospitalizationDiagnostic test sensitivitySensitive testAdultsSurveillance systemChildrenYearsPneumonia among adults hospitalized with laboratory-confirmed seasonal influenza virus infection—United States, 2005–2008
Garg S, Jain S, Dawood FS, Jhung M, Pérez A, D’Mello T, Reingold A, Gershman K, Meek J, Arnold KE, Farley MM, Ryan P, Lynfield R, Morin C, Baumbach J, Hancock EB, Zansky S, Bennett N, Thomas A, Schaffner W, Finelli L. Pneumonia among adults hospitalized with laboratory-confirmed seasonal influenza virus infection—United States, 2005–2008. BMC Infectious Diseases 2015, 15: 369. PMID: 26307108, PMCID: PMC4550040, DOI: 10.1186/s12879-015-1004-y.Peer-Reviewed Original ResearchConceptsIntensive care unit admissionSeasonal influenza virus infectionICD-9-CM codesCertain underlying conditionsEmerging Infections ProgramCare unit admissionLaboratory-confirmed influenzaInfluenza virus infectionCause of deathCXR infiltrateUnit admissionICU admissionOlder patientsMechanical ventilationMultivariable analysisUnderlying conditionInfections ProgramChest radiographsVirus infectionPneumoniaSummary diagnosisInfectious diseasesInfluenzaPatientsAdultsObesity not associated with severity among hospitalized adults with seasonal influenza virus infection
Braun ES, Crawford FW, Desai MM, Meek J, Kirley PD, Miller L, Anderson EJ, Oni O, Ryan P, Lynfield R, Bargsten M, Bennett NM, Lung KL, Thomas A, Mermel E, Lindegren ML, Schaffner W, Price A, Chaves SS. Obesity not associated with severity among hospitalized adults with seasonal influenza virus infection. Infection 2015, 43: 569-575. PMID: 26148927, DOI: 10.1007/s15010-015-0802-x.Peer-Reviewed Original ResearchConceptsSeasonal influenza virus infectionMultivariate logistic regression modelSeasonal influenza severityLaboratory-confirmed influenzaRisk of pneumoniaInfluenza virus infectionLogistic regression modelsHospitalized adultsICU admissionObese patientsSevere obesityInfluenza severityArtificial ventilationVirus infectionWeight categoriesObesityPneumoniaSeverityRegression modelsAdultsUnderweightPatientsAdmissionInfectionInfluenzaDoes Influenza Vaccination Modify Influenza Severity? Data on Older Adults Hospitalized With Influenza During the 2012−2013 Season in the United States
Arriola C, Anderson E, Baumbach J, Bennett N, Bohm S, Hill M, Lindegren M, Lung K, Meek J, Mermel E, Miller L, Monroe M, Morin C, Oni O, Reingold A, Schaffner W, Thomas A, Zansky S, Finelli L, Chaves S. Does Influenza Vaccination Modify Influenza Severity? Data on Older Adults Hospitalized With Influenza During the 2012−2013 Season in the United States. The Journal Of Infectious Diseases 2015, 212: 1200-1208. PMID: 25821227, PMCID: PMC4683374, DOI: 10.1093/infdis/jiv200.Peer-Reviewed Original ResearchConceptsInfluenza vaccinationInfluenza severityDisease severityIntensive care unit admissionMultivariable logistic regression modelSevere influenza outcomesCare unit admissionLaboratory-confirmed influenzaMultivariable logistic regressionDiagnosis of pneumoniaLogistic regression modelsUnit admissionICU lengthVaccine effectivenessInfluenza seasonParametric survival modelsInfluenza outcomesVaccinated personsVaccinationPropensity scoreLogistic regressionOlder adultsPredominant strainSeverityInfluenza
2014
The Burden of Influenza Hospitalizations in Infants From 2003 to 2012, United States
Chaves S, Perez A, Farley M, Miller L, Schaffner W, Lindegren M, Sharangpani R, Meek J, Yousey-Hindes K, Thomas A, Boulton R, Baumbach J, Hancock E, Bandyopadhyay A, Lynfield R, Morin C, Zansky S, Reingold A, Bennett N, Ryan P, Fowler B, Fry A, Finelli L. The Burden of Influenza Hospitalizations in Infants From 2003 to 2012, United States. The Pediatric Infectious Disease Journal 2014, 33: 912-919. PMID: 24577042, DOI: 10.1097/inf.0000000000000321.Peer-Reviewed Original ResearchConceptsImpact of influenzaHigh-risk conditionsHospitalization ratesRisk factorsOlder infantsIntensive care unit admissionInfluenza-associated hospitalization ratesCare unit admissionRisk conditionsInfluenza hospitalizationsUnit admissionICU admissionInfluenza vaccinationRespiratory failureClinical characteristicsInfant hospitalizationHealthy infantsMost hospitalizationsPregnant womenLung diseaseCardiovascular diseaseUS infantsHospitalizationYoung infantsInfantsChild, Household, and Caregiver Characteristics Associated with Hospitalization for Influenza Among Children 6–59 Months of Age
Dharan N, Sokolow L, Cheng P, Gargiullo P, Gershman K, Lynfield R, Morin C, Thomas A, Meek J, Farley M, Arnold K, Reingold A, Craig A, Schaffner W, Bennett N, Zansky S, Baumbach J, Lathrop S, Kamimoto L, Shay D. Child, Household, and Caregiver Characteristics Associated with Hospitalization for Influenza Among Children 6–59 Months of Age. The Pediatric Infectious Disease Journal 2014, 33: e141-e150. PMID: 24642518, PMCID: PMC4025593, DOI: 10.1097/inf.0000000000000283.Peer-Reviewed Original ResearchConceptsMonths of ageChildren 6Influenza hospitalizationsInfluenza illnessInfluenza vaccinationMaternal ageRisk factorsSevere outcomesChronic illnessEmerging Infections Program sitesLaboratory-confirmed influenza infectionIndependent risk factorInfluenza-associated hospitalizationsYoung maternal ageCase-control studyConditional logistic regressionYoung childrenHematologic/Influenza immunizationHousehold smokingEligible casesInfluenza infectionNeurologic conditionsEligible controlsMedical recordsComplications Among Adults Hospitalized With Influenza: A Comparison of Seasonal Influenza and the 2009 H1N1 Pandemic
Reed C, Chaves S, Perez A, D'Mello T, Kirley P, Aragon D, Meek J, Farley M, Ryan P, Lynfield R, Morin C, Hancock E, Bennett N, Zansky S, Thomas A, Lindegren M, Schaffner W, Finelli L. Complications Among Adults Hospitalized With Influenza: A Comparison of Seasonal Influenza and the 2009 H1N1 Pandemic. Clinical Infectious Diseases 2014, 59: 166-174. PMID: 24785230, PMCID: PMC7314251, DOI: 10.1093/cid/ciu285.Peer-Reviewed Original ResearchMeSH KeywordsAdultAge FactorsAgedAged, 80 and overFemaleHospitalizationHumansInfluenza A Virus, H1N1 SubtypeInfluenza, HumanMaleMiddle AgedConceptsSeasonal influenzaMedical conditionsLower respiratory tract complicationsRevision discharge diagnosis codesPopulation-based surveillance systemCertain underlying medical conditionsYoung adultsInfluenza-associated complicationsInfluenza-related complicationsShock/sepsisTypical influenza seasonPattern of complicationsRespiratory tract complicationsUnderlying medical conditionsDischarge diagnosis codesChronic medical conditionsIntensive care unitAppropriate clinical managementSevere influenzaNeurologic complicationsInfluenza seasonOrgan failureCare unitMechanical ventilationClinical complications
2013
Complications and Associated Bacterial Coinfections Among Children Hospitalized With Seasonal or Pandemic Influenza, United States, 2003–2010
Dawood F, Chaves S, Pérez A, Reingold A, Meek J, Farley M, Ryan P, Lynfield R, Morin C, Baumbach J, Bennett N, Zansky S, Thomas A, Lindegren M, Schaffner W, Finelli L, Network F. Complications and Associated Bacterial Coinfections Among Children Hospitalized With Seasonal or Pandemic Influenza, United States, 2003–2010. The Journal Of Infectious Diseases 2013, 209: 686-694. PMID: 23986545, DOI: 10.1093/infdis/jit473.Peer-Reviewed Original ResearchConceptsIntensive carePandemic influenzaLaboratory-confirmed influenza hospitalizationsBacteremia/sepsisInfluenza-associated complicationsIntensive care requirementAcute renal failurePopulation-based surveillanceSeverity of complicationsMedian hospitalization durationNinth Revision codesInfluenza hospitalizationsAsthma exacerbationsHospitalization durationInfluenza vaccinationRespiratory failureCommon complicationRenal failureBacterial coinfectionProlonged hospitalizationMedian lengthPrimary preventionRevision codesSeasonal influenzaHospitalized childrenEffectiveness of Nonadjuvanted Monovalent Influenza A(H1N1)pdm09 Vaccines for Preventing Reverse Transcription Polymerase Chain Reaction–Confirmed Pandemic Influenza Hospitalizations: Case-Control Study of Children and Adults at 10 US Influenza Surveillance Network Sites
Thompson M, Sokolow L, Almendares O, Openo K, Farley M, Meek J, Ray J, Kirley P, Reingold A, Aragon D, Hancock E, Baumbach J, Schaffner W, Thomas A, Lynfield R, Ryan P, Monroe M, Cheng P, Fry A, Shay D. Effectiveness of Nonadjuvanted Monovalent Influenza A(H1N1)pdm09 Vaccines for Preventing Reverse Transcription Polymerase Chain Reaction–Confirmed Pandemic Influenza Hospitalizations: Case-Control Study of Children and Adults at 10 US Influenza Surveillance Network Sites. Clinical Infectious Diseases 2013, 57: 1587-1592. PMID: 23956169, PMCID: PMC7314184, DOI: 10.1093/cid/cit551.Peer-Reviewed Original ResearchConceptsLaboratory-confirmed pandemic influenzaCommunity-matched controlsCase-control studyReverse transcription-polymerase chain reactionTranscription-polymerase chain reactionInfluenza hospitalizationsMonovalent influenzaPandemic influenzaSingle dosePolymerase chain reactionVirus infectionInfluenzaChain reactionHospitalizationVaccinePatientsInfectionDose
2012
Guillain-Barré Syndrome During the 2009–2010 H1N1 Influenza Vaccination Campaign: Population-based Surveillance Among 45 Million Americans
Wise M, Viray M, Sejvar J, Lewis P, Baughman A, Connor W, Danila R, Giambrone G, Hale C, Hogan B, Meek J, Murphree R, Oh J, Reingold A, Tellman N, Conner S, Singleton J, Lu P, DeStefano F, Fridkin S, Vellozzi C, Morgan O. Guillain-Barré Syndrome During the 2009–2010 H1N1 Influenza Vaccination Campaign: Population-based Surveillance Among 45 Million Americans. American Journal Of Epidemiology 2012, 175: 1110-1119. PMID: 22582209, PMCID: PMC3888111, DOI: 10.1093/aje/kws196.Peer-Reviewed Original ResearchMeSH KeywordsAdolescentAdultAgedChildChild, PreschoolFemaleGuillain-Barre SyndromeHealth PromotionHumansIncidenceInfantInfluenza A Virus, H1N1 SubtypeInfluenza VaccinesInfluenza, HumanMaleMiddle AgedPopulation SurveillanceProduct Surveillance, PostmarketingRisk AssessmentTime FactorsUnited StatesYoung AdultConceptsGuillain-Barré syndromePopulation-based surveillanceGBS casesPH1N1 vaccineInfluenza A (H1N1) 2009 monovalent vaccineRate of GBSEmerging Infections Program sitesSex-adjusted rate ratiosH1N1 influenza vaccineMedical record reviewVaccine coverage dataInfluenza vaccination campaignGBS incidencePH1N1 vaccinationInfluenza vaccineMonovalent vaccineRecord reviewIncident casesVaccine dosesExcess riskPatient interviewsGBS riskVaccine campaignVaccine historyVaccination campaignReduced Influenza Antiviral Treatment Among Children and Adults Hospitalized With Laboratory-Confirmed Influenza Infection in the Year After the 2009 Pandemic
Garg S, Chaves SS, Pérez A, D'Mello T, Gershman K, Meek J, Yousey-Hindes K, Arnold KE, Farley MM, Tengelsen L, Ryan P, Sharangpani R, Lynfield R, Morin C, Baumbach J, Hancock EB, Zansky S, Bennett NM, Fowler B, Bradley K, Thomas A, Cooper T, Schaffner W, Boulton R, Finelli L, Fry AM. Reduced Influenza Antiviral Treatment Among Children and Adults Hospitalized With Laboratory-Confirmed Influenza Infection in the Year After the 2009 Pandemic. Clinical Infectious Diseases 2012, 55: e18-e21. PMID: 22543024, DOI: 10.1093/cid/cis442.Peer-Reviewed Original ResearchInfluenza-associated Hospitalizations by Industry, 2009–10 Influenza Season, United States - Volume 18, Number 4—April 2012 - Emerging Infectious Diseases journal - CDC
Luckhaupt SE, Sweeney MH, Funk R, Calvert GM, Nowell M, D'Mello T, Reingold A, Meek J, Yousey-Hindes K, Arnold KE, Ryan P, Lynfield R, Morin C, Baumbach J, Zansky S, Bennett NM, Thomas A, Schaffner W, Jones T. Influenza-associated Hospitalizations by Industry, 2009–10 Influenza Season, United States - Volume 18, Number 4—April 2012 - Emerging Infectious Diseases journal - CDC. Emerging Infectious Diseases 2012, 18: 556-562. PMID: 22469504, PMCID: PMC3309704, DOI: 10.3201/eid1804.110337.Peer-Reviewed Original Research