Nallakkandi Rajeevan, PhD
Senior Research Scientist of Biomedical Informatics and Data ScienceDownloadHi-Res Photo
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Associate Director for Bioinformatics, Yale Center for Medical Informatics
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Appointments
Additional Titles
Associate Director for Bioinformatics, Yale Center for Medical Informatics
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Appointments
Additional Titles
Associate Director for Bioinformatics, Yale Center for Medical Informatics
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Senior Research Scientist of Biomedical Informatics and Data Science
Associate Director for Bioinformatics, Yale Center for Medical Informatics
Biography
Dr. Rajeevan's research focuses on applying his deep knowledge in theoretical computer science, algorithm development, statistical estimation theory, and biostatistics to problems in genomics, bioinformatics, nuclear medicine and functional brain imaging. He received his B.E., M.S., and Ph.D. from Indian Institute of Science, Bangalore, India and did his post-doctoral fellowship in Nuclear Medicine from University of Massachusetts Medical Center, Worcester, MA.
Last Updated on April 07, 2025.
Appointments
Biomedical Informatics & Data Science
Senior Research ScientistPrimary
Other Departments & Organizations
- Biomedical Informatics & Data Science
- Genomics, Genetics, and Epigenetics
- Yale Cancer Center
- Yale-BI Biomedical Data Science Fellowship
Education & Training
- Post-doctoral fellow
- University of Massachusetts Medical Center (1993)
- PhD
- Indian Institute of Science (1992)
- MS
- Indian Institute of Science, Electrical Engineering (1986)
- BE
- Indian Institute of Science, Electronics and Communications (1979)
Research
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Overview
Medical Research Interests
Information Science
Public Health Interests
Bioinformatics; Cancer; Genetics, Genomics, Epigenetics
ORCID
0000-0002-2045-0872
Research at a Glance
Yale Co-Authors
Frequent collaborators of Nallakkandi Rajeevan's published research.
Publications Timeline
A big-picture view of Nallakkandi Rajeevan's research output by year.
Mihaela Aslan, PhD
Lei Yan, PhD
Hongyu Zhao, PhD
John Seibyl, MD
Yuan Huang, PhD
Hung-Mo Lin
87Publications
4,542Citations
Publications
Featured Publications
Effectiveness of Nirmatrelvir-Ritonavir Against the Development of Post-COVID-19 Conditions Among U.S. Veterans : A Target Trial Emulation.
Ioannou G, Berry K, Rajeevan N, Li Y, Mutalik P, Yan L, Bui D, Cunningham F, Hynes D, Rowneki M, Bohnert A, Boyko E, Iwashyna T, Maciejewski M, Osborne T, Viglianti E, Aslan M, Huang G, Bajema K. Effectiveness of Nirmatrelvir-Ritonavir Against the Development of Post-COVID-19 Conditions Among U.S. Veterans : A Target Trial Emulation. Annals Of Internal Medicine 2023, 176: 1486-1497. PMID: 37903369, PMCID: PMC10620954, DOI: 10.7326/m23-1394.Peer-Reviewed Original ResearchCitationsAltmetricMeSH Keywords and ConceptsConceptsAcute COVID-19Veterans Health AdministrationUntreated comparatorsThromboembolic eventsCOVID-19Severe COVID-19Target trial emulationSARS-CoV-2Post COVID-19 conditionIndex dateVenous thromboembolismBaseline characteristicsCumulative incidencePulmonary embolismAcute infectionMedian ageOral antiviralsTrial emulationVHA careOutpatient treatmentInternational ClassificationHealth AdministrationU.S. veteransVeterans AffairsOrgan systems
2025
Durability of Respiratory Syncytial Virus Vaccine Effectiveness Among US Veterans
Bajema K, Bui D, Yan L, Li Y, Rajeevan N, Vergun R, Sriskantharajah V, Hynes D, Berry K, Huang Y, Lin H, Aslan M, Ioannou G. Durability of Respiratory Syncytial Virus Vaccine Effectiveness Among US Veterans. JAMA Internal Medicine 2025, 186 PMID: 41284307, PMCID: PMC12645397, DOI: 10.1001/jamainternmed.2025.6355.Peer-Reviewed Original ResearchCitationsAltmetricConceptsRespiratory syncytial virus vaccineRespiratory syncytial virusIntensive care unit admissionRSV vaccineVaccine effectivenessUnit admissionRespiratory syncytial virus illnessSevere respiratory syncytial virusVaccine doseRespiratory syncytial virus infectionMonths of follow-upLong-term effectsHealth care useRespiratory illness seasonVeterans Health AdministrationMatched index dateUrgent care visitsTarget trial emulationMedian ageCare useCare visitsSingle doseSyncytial virusIndex dateVaccine recipientsImpact of time zero designation on estimated COVID-19 antiviral effectiveness in observational studies
Bajema K, Yan L, Berry K, Bui D, Lin H, Huang Y, Li Y, Rajeevan N, Maciejewski M, Smith V, Bohnert A, Hynes D, Aslan M, Ioannou G. Impact of time zero designation on estimated COVID-19 antiviral effectiveness in observational studies. American Journal Of Epidemiology 2025, kwaf221. PMID: 41078178, DOI: 10.1093/aje/kwaf221.Peer-Reviewed Original ResearchBudget Impact of Adopting Nirmatrelvir-Ritonavir for Treating COVID-19 in a Large Integrated Healthcare System
Bui D, Hynes D, Wong E, Vergun R, Yan L, Li Y, Rajeevan N, Berry K, Lin H, Huang Y, Govier D, Aslan M, Ioannou G, Bajema K. Budget Impact of Adopting Nirmatrelvir-Ritonavir for Treating COVID-19 in a Large Integrated Healthcare System. Open Forum Infectious Diseases 2025, 12: ofaf596. PMID: 41089767, PMCID: PMC12517272, DOI: 10.1093/ofid/ofaf596.Peer-Reviewed Original ResearchAltmetricConceptsVeterans Health AdministrationHealthcare systemEmergency departmentBudget impactRisk quartileIntegrated healthcare systemHealthcare utilization costsHealthcare cost savingsHighest risk quartileTarget trial emulationHealth AdministrationHealthcare costsTrial emulationHealthcareCOVID-19VeteransHospitalTargeted treatmentQuartileClinical subgroupsUtilization costsTreatment benefitTargeted treatment of patientsCost savingsTreatment of patientsCombining Rule-based NLP-lite with Rapid Iterative Chart Adjudication for Creation of a Large, Accurately Curated Cohort from EHR data: A Case Study in the Context of a Clinical Trial Emulation.
Mutalik P, Cheung K, Green J, Buelt-Gebhardt M, Anderson K, Jeanpaul V, McDonald L, Wininger M, Li Y, Rajeevan N, Jessel P, Moore H, Adabag S, Raitt M, Aslan M. Combining Rule-based NLP-lite with Rapid Iterative Chart Adjudication for Creation of a Large, Accurately Curated Cohort from EHR data: A Case Study in the Context of a Clinical Trial Emulation. AMIA Annual Symposium Proceedings 2025, 2024: 847-856. PMID: 40417550, PMCID: PMC12099393.Peer-Reviewed Original ResearchMeSH Keywords and ConceptsConceptsCorporate Data WarehouseNon-expertsClinical AI applicationsData warehouseAI applicationsVirtual emulationEHR dataClinical decision criteriaExtract informationCurated datasetComputational algorithmDecision criteriaTraining toolEmulationClinical notesStructural dataCase studyAlgorithmEHRDatasetWarehouseComputerInclusion/exclusion decisionsTarget Trial Emulation of SARS-CoV-2 Infection Versus No Infection and Risk of Post–COVID-19 Conditions in the Omicron Variant Versus Prior Eras
Ioannou G, Berry K, Rajeevan N, Li Y, Yan L, Huang Y, Bui D, Hynes D, Rowneki M, Hickok A, Niederhausen M, Shahoumian T, Bohnert A, Boyko E, Korpak A, Fox A, Baraff A, Iwashyna T, Maciejewski M, Smith V, Berkowitz T, Pura J, Hebert P, Wong E, O’Hare A, Osborne T, Viglianti E, Aslan M, Bajema K. Target Trial Emulation of SARS-CoV-2 Infection Versus No Infection and Risk of Post–COVID-19 Conditions in the Omicron Variant Versus Prior Eras. Clinical Infectious Diseases 2025, 81: 10-19. PMID: 40208261, DOI: 10.1093/cid/ciaf087.Peer-Reviewed Original ResearchCitationsAltmetricConceptsPost-COVID-19 conditionCumulative incidence of deathVeterans Health AdministrationMatched index dateCumulative incidence differenceExcess burdenCumulative incidenceBurden of mortalityHypothetical target trialIncidence of deathDeath up to 1 yearTarget trial emulationAll-Cause MortalityHealth recordsHealth AdministrationTrial emulationIncidence differencesIndex dateUninfected participantsPost-coronavirus diseaseVeteransUnvaccinated personsTarget trialsOmicron eraVaccination statusSeverity and Long-Term Mortality of COVID-19, Influenza, and Respiratory Syncytial Virus
Bajema K, Bui D, Yan L, Li Y, Rajeevan N, Vergun R, Berry K, Huang Y, Lin H, Aslan M, Ioannou G. Severity and Long-Term Mortality of COVID-19, Influenza, and Respiratory Syncytial Virus. JAMA Internal Medicine 2025, 185: 324-334. PMID: 39869355, PMCID: PMC11773409, DOI: 10.1001/jamainternmed.2024.7452.Peer-Reviewed Original ResearchCitationsAltmetricMeSH Keywords and ConceptsConceptsRespiratory syncytial virusLong-term mortalitySARS-CoV-2Syncytial virusCohort studyAssociated with higher long-term mortalityRisk differenceIntensive care unit admissionSeasonal influenza vaccineRetrospective cohort studyDisease severity of COVID-19Long-term deathAssociated with more severe disease outcomesRisk of deathCompare disease severitySevere disease outcomesRisk of hospitalizationSeverity of COVID-19Same-day testingInfluenza vaccineInverse probability weightingUnit admissionCumulative incidenceMortality of COVID-19Primary outcomeEffectiveness of the 2023-to-2024 XBB.1.5 COVID-19 Vaccines Over Long-Term Follow-up : A Target Trial Emulation.
Ioannou G, Berry K, Rajeevan N, Li Y, Yan L, Huang Y, Lin H, Bui D, Hynes D, Rowneki M, Bohnert A, Boyko E, Iwashyna T, Maciejewski M, Smith V, Berkowitz T, O'Hare A, Viglianti E, Aslan M, Bajema K. Effectiveness of the 2023-to-2024 XBB.1.5 COVID-19 Vaccines Over Long-Term Follow-up : A Target Trial Emulation. Annals Of Internal Medicine 2025, 178: 348-359. PMID: 39903865, DOI: 10.7326/annals-24-01015.Peer-Reviewed Original ResearchCitationsAltmetricMeSH Keywords and ConceptsConceptsU.S. Department of Veterans AffairsDepartment of Veterans AffairsMatched index dateVaccine effectivenessTarget trial emulationSARS-CoV-2-associated deathsRandomized Controlled TrialsCOVID-19 vaccineSARS-CoV-2-related outcomesSARS-CoV-2 testingVeterans AffairsResidual confoundingAbsence of randomized controlled trialsLong-term follow-upDocumented SARS-CoV-2 infectionTrial emulationUnvaccinated personsIndex datePositive resultsControlled TrialsCOVID-19SARS-CoV-2 infectionIncomplete captureHospitalDocumented infectionRespiratory syncytial virus vaccine effectiveness among US veterans, September, 2023 to March, 2024: a target trial emulation study
Bajema K, Yan L, Li Y, Argraves S, Rajeevan N, Fox A, Vergun R, Berry K, Bui D, Huang Y, Lin H, Hynes D, Lucero-Obusan C, Schirmer P, Cunningham F, Huang G, Aslan M, Ioannou G. Respiratory syncytial virus vaccine effectiveness among US veterans, September, 2023 to March, 2024: a target trial emulation study. The Lancet Infectious Diseases 2025, 25: 625-633. PMID: 39848264, DOI: 10.1016/s1473-3099(24)00796-5.Peer-Reviewed Original ResearchCitationsAltmetricConceptsRespiratory syncytial virusRespiratory syncytial virus vaccinePositive RSV testVaccine effectivenessRSV testCare encountersSecondary outcomesEmergency departmentRSV-associated hospitalisationsMedian Follow-UpUS Food and Drug AdministrationHealth-care useVeterans Health AdministrationRespiratory illness seasonMatched index dateElectronic health recordsLower respiratory tract diseaseRSV-related illnessFood and Drug AdministrationDepartment of Veterans Affairs Cooperative Studies ProgramVeterans Affairs Cooperative Studies ProgramCooperative Studies ProgramRSV infectionMedian ageUS Department
2024
Development of a prediction model for 30-day COVID-19 hospitalization and death in a national cohort of Veterans Health Administration patients–March 2022—April 2023
Bui D, Bajema K, Huang Y, Yan L, Li Y, Rajeevan N, Berry K, Rowneki M, Argraves S, Hynes D, Huang G, Aslan M, Ioannou G. Development of a prediction model for 30-day COVID-19 hospitalization and death in a national cohort of Veterans Health Administration patients–March 2022—April 2023. PLOS ONE 2024, 19: e0307235. PMID: 39365775, PMCID: PMC11451987, DOI: 10.1371/journal.pone.0307235.Peer-Reviewed Original ResearchCitationsMeSH Keywords and ConceptsConceptsVeterans Health AdministrationCOVID-19 hospitalizationArea under the receiver operating characteristic curveComprehensive electronic health recordNational cohortElectronic health recordsAll-Cause MortalityNational cohort of patientsFull modelHealth recordsHealth AdministrationReceipt of COVID-19 vaccineMortality riskEpidemiology of COVID-19COVID-19High-risk patientsBrier scoreCohort of patientsAnti-SARS-CoV-2 treatmentCOVID-19 vaccineReceiver operating characteristic curveCalibration interceptHospitalAntiviral treatmentAvailability of effective vaccines
Academic Achievements & Community Involvement
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Honors
honor Life Senior Member
10/26/2021International AwardInstitute of Electrical and Electronics Engineers (IEEE), Inc., New YorkDetailsUnited Stateshonor Lifetime Service Award
06/01/2010International AwardIndo-American Society of Nuclear MedicineDetailsUnited States
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