Frederick Warner, PhD
Associate Research ScientistCards
About
Research
Publications
2026
Ocular Symptoms in Long COVID: A Cross-Sectional Study
Kaleem S, Sawano M, Arun A, Warner F, Zhou T, Huang C, Bhattacharjee B, Lu Y, Iwasaki A, Nwanyanwu K, Ahmed I, Krumholz H. Ocular Symptoms in Long COVID: A Cross-Sectional Study. Clinical Ophthalmology 2026, Volume 20 DOI: 10.2147/OPTH.S565596.Peer-Reviewed Original Research
2025
Update to the JACC Report Card Excess Cardiovascular Mortality Among Black Americans, 2000-2023
Arun A, Sawano M, Lu Y, Warner F, Caraballo C, Khera R, Echols M, Yancy C, Krumholz H. Update to the JACC Report Card Excess Cardiovascular Mortality Among Black Americans, 2000-2023. Journal Of The American College Of Cardiology 2025, 86: 559-562. PMID: 40835364, DOI: 10.1016/j.jacc.2025.06.008.Peer-Reviewed Original ResearchNirmatrelvir–ritonavir versus placebo–ritonavir in individuals with long COVID in the USA (PAX LC): a double-blind, randomised, placebo-controlled, phase 2, decentralised trial
Sawano M, Bhattacharjee B, Caraballo C, Khera R, Li S, Herrin J, Christian D, Coppi A, Warner F, Holub J, Henriquez Y, Johnson M, Goddard T, Rocco E, Hummel A, Mouslmani M, Hooper W, Putrino D, Carr K, Charnas L, De Jesus M, Nepert D, Abreu P, Ziegler F, Spertus J, Iwasaki A, Krumholz H. Nirmatrelvir–ritonavir versus placebo–ritonavir in individuals with long COVID in the USA (PAX LC): a double-blind, randomised, placebo-controlled, phase 2, decentralised trial. The Lancet Infectious Diseases 2025, 25: 936-946. PMID: 40188838, DOI: 10.1016/s1473-3099(25)00073-8.Peer-Reviewed Original ResearchPhysical health summary scoreBaseline to dayAdverse eventsNirmatrelvir-ritonavirSARS-CoV-2 infectionDouble-blindStudy drug-related treatment-emergent adverse eventsDrug-related treatment-emergent adverse eventsTreatment-emergent adverse eventsIntention-to-treat populationWeek 6Baseline to week 6Documented SARS-CoV-2 infectionActive liver diseaseEffective pharmacological interventionsLong COVIDAcute medical illnessSafety populationPatient-Reported Outcomes Measurement Information SystemEarly treatment terminationRenal impairmentTreat long-COVIDPlacebo-ControlledEfficacy endpointRandomised controlled trialsAssessment of health conditions from patient electronic health record portals vs self-reported questionnaires: an analysis of the INSPIRE study
Khera R, Sawano M, Warner F, Coppi A, Pedroso A, Spatz E, Yu H, Gottlieb M, Saydah S, Stephens K, Rising K, Elmore J, Hill M, Idris A, Montoy J, O’Laughlin K, Weinstein R, Venkatesh A, Weinstein R, Gottlieb M, Santangelo M, Koo K, Derden A, Gottlieb M, Gatling K, Ahmed Z, Gomez C, Guzman D, Hassaballa M, Jerger R, Kaadan A, Venkatesh A, Spatz E, Kinsman J, Malicki C, Lin Z, Li S, Yu H, Mannan I, Yang Z, Liu M, Venkatesh A, Spatz E, Ulrich A, Kinsman J, Malicki C, Dorney J, Pierce S, Puente X, Salah W, Nichol G, Stephens K, Anderson J, Schiffgens M, Morse D, Adams K, Stober T, Maat Z, O’Laughlin K, Gentile N, Geyer R, Willis M, Zhang Z, Chang G, Lyon V, Klabbers R, Ruiz L, Malone K, Park J, Rising K, Kean E, Chang A, Renzi N, Watts P, Kelly M, Schaeffer K, Grau D, Cheng D, Shutty C, Charlton A, Shughart L, Shughart H, Amadio G, Miao J, Hannikainen P, Elmore J, Wisk L, L’Hommedieu M, Chandler C, Eguchi M, Roldan K, Moreno R, Rodriguez R, Wang R, Montoy J, Kemball R, Chan V, Chavez C, Wong A, Arreguin M, Hill M, Site R, Kane A, Nikonowicz P, Sapp S, Idris A, McDonald S, Gallegos D, Martin K, Saydah S, Plumb I, Hall A, Briggs-Hagen M. Assessment of health conditions from patient electronic health record portals vs self-reported questionnaires: an analysis of the INSPIRE study. Journal Of The American Medical Informatics Association 2025, 32: 784-794. PMID: 40036551, PMCID: PMC12012333, DOI: 10.1093/jamia/ocaf027.Peer-Reviewed Original ResearchElectronic health recordsSelf-report questionnairesSelf-ReportHealth conditionsElectronic health record portalsElectronic health record platformsEHR elementsSelf-reported health conditionsElectronic health record dataSelf-reported conditionsAssessment of health conditionEvaluation of health conditionsPrevalence of conditionsPatient portalsTraditional self-reportPrevalence of comorbiditiesHealth recordsEHR dataEHR phenotypesDiagnosis codesHospitalization riskComputable phenotypeNationwide studyCohen's kappaPatient characteristics
2024
Internal Tremors and Vibrations in Long COVID: A Cross-Sectional Study
Zhou T, Sawano M, Arun A, Caraballo C, Michelsen T, McAlpine L, Bhattacharjee B, Lu Y, Khera R, Huang C, Warner F, Herrin J, Iwasaki A, Krumholz H. Internal Tremors and Vibrations in Long COVID: A Cross-Sectional Study. The American Journal Of Medicine 2024, 138: 1010-1018.e14. PMID: 39069199, PMCID: PMC12023347, DOI: 10.1016/j.amjmed.2024.07.008.Peer-Reviewed Original ResearchNew-onset conditionsInternal tremorLong COVID symptomsCOVID symptomsNon-Hispanic whitesCross-sectional studyQuality of lifeVisual analogue scaleWorse healthHealth statusStudy participantsDemographic characteristicsAnalogue scaleOutcome variablesNeurological conditionsLong COVIDMast cell disordersTreatment experienceHealthComorbiditiesSymptomsMedian agePeopleCell disordersExcess Cardiovascular Mortality Among Black Americans 2000-2022
Arun A, Sawano M, Lu Y, Warner F, Caraballo C, Khera R, Echols M, Yancy C, Krumholz H. Excess Cardiovascular Mortality Among Black Americans 2000-2022. Journal Of The American College Of Cardiology 2024, 84: 581-588. PMID: 38901531, DOI: 10.1016/j.jacc.2024.06.004.Peer-Reviewed Original ResearchLong COVID Characteristics and Experience: A Descriptive Study From the Yale LISTEN Research Cohort
Sawano M, Wu Y, Shah R, Zhou T, Arun A, Khosla P, Kaleem S, Vashist A, Bhattacharjee B, Ding Q, Lu Y, Caraballo C, Warner F, Huang C, Herrin J, Putrino D, Michelsen T, Fisher L, Adinig C, Iwasaki A, Krumholz H. Long COVID Characteristics and Experience: A Descriptive Study From the Yale LISTEN Research Cohort. The American Journal Of Medicine 2024, 138: 712-720.e13. PMID: 38663793, DOI: 10.1016/j.amjmed.2024.04.015.Peer-Reviewed Original ResearchExperiences of peopleHealth statusLong COVIDLower health statusNew-onset conditionsCommunity support servicesNon-Hispanic whitesArray of healthQuality of lifeVisual analogue scaleMental healthPsychological distressPsychological statusDescriptive studyHealthcare systemMedian scoreSupport servicesResearch cohortSocial isolationDemographic characteristicsAnalogue scaleImpact of long COVIDHealthFinancial stressParticipants
2022
Association between primary or booster COVID-19 mRNA vaccination and Omicron lineage BA.1 SARS-CoV-2 infection in people with a prior SARS-CoV-2 infection: A test-negative case–control analysis
Lind M, Robertson A, Silva J, Warner F, Coppi A, Price N, Duckwall C, Sosensky P, Di Giuseppe E, Borg R, Fofana M, Ranzani O, Dean N, Andrews J, Croda J, Iwasaki A, Cummings D, Ko A, Hitchings M, Schulz W. Association between primary or booster COVID-19 mRNA vaccination and Omicron lineage BA.1 SARS-CoV-2 infection in people with a prior SARS-CoV-2 infection: A test-negative case–control analysis. PLOS Medicine 2022, 19: e1004136. PMID: 36454733, PMCID: PMC9714718, DOI: 10.1371/journal.pmed.1004136.Peer-Reviewed Original ResearchConceptsSARS-CoV-2 infectionBooster vaccinationPrior infectionOmicron infectionPrimary vaccinationMRNA vaccinationOdds ratioAcute respiratory syndrome coronavirus 2 infectionSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infectionPrior SARS-CoV-2 infectionTest-negative case-control analysisYale New Haven Health SystemTest-negative case-control studyCOVID-19 mRNA vaccinationSyndrome coronavirus 2 infectionOmicron variant infectionPrior infection statusCoronavirus 2 infectionCase-control studyCase-control analysisOdds of infectionRisk of infectionRace/ethnicityBooster dosesDate of testUse of Whole-Genome Sequencing to Estimate the Contribution of Immune Evasion and Waning Immunity on Decreasing COVID-19 Vaccine Effectiveness
Lind M, Copin R, McCarthy S, Coppi A, Warner F, Ferguson D, Duckwall C, Borg R, Muenker M, Overton J, Hamon S, Zhou A, Cummings D, Ko A, Hamilton J, Schulz W, Hitchings M. Use of Whole-Genome Sequencing to Estimate the Contribution of Immune Evasion and Waning Immunity on Decreasing COVID-19 Vaccine Effectiveness. Journal Of Infectious Diseases 2022, 227: 663-674. PMID: 36408616, DOI: 10.1093/infdis/jiac453.Peer-Reviewed Original ResearchConceptsVaccine effectivenessImmune evasionDelta infectionVE estimatesSecond doseTest-negative case-control studySevere acute respiratory syndrome coronavirus 2Acute respiratory syndrome coronavirus 2Whole-genome sequencingCOVID-19 vaccine effectivenessRespiratory syndrome coronavirus 2Syndrome coronavirus 2Case-control studyCoronavirus 2Calendar periodDelta variantInfectionDoseEvasionDaysLow effectivenessImmunityVariants
2010
Diffusion Geometry Based Nonlinear Methods for Hyperspectral Change Detection
Coifman R, Coppi A, Hirn M, Warner F. Diffusion Geometry Based Nonlinear Methods for Hyperspectral Change Detection. 2010 DOI: 10.21236/ada524546.Peer-Reviewed Original ResearchSignal processing algorithmsChange detectionNonlinear signal processing algorithmsHyperspectral Change DetectionGroups of featuresProcessing algorithmsSpatio-spectral featuresProcessing toolboxSegmentation methodologyFeature spaceInvariant featuresSpectral signaturesHyperspectral imagesAnomaly assessmentTarget detectionDifferent conditionsDiffusion geometryTerms of similarityNonlinear methodsSceneGeometry