2024
Effectiveness of the fourth dose of COVID-19 vaccines against severe COVID-19 among adults 40 years or older in Brazil: a population-based cohort study
Neto F, Hitchings M, Amin A, de França G, Lind M, Torres M, Tsuha D, de Oliveira R, Cummings D, Dean N, Andrews J, Ko A, Croda J, Ranzani O. Effectiveness of the fourth dose of COVID-19 vaccines against severe COVID-19 among adults 40 years or older in Brazil: a population-based cohort study. The Lancet Regional Health - Americas 2024, 34: 100755. PMID: 38737773, PMCID: PMC11087726, DOI: 10.1016/j.lana.2024.100755.Peer-Reviewed Original ResearchSevere COVID-19Cohort ACohort B.Cohort BTwo-doseMRNA vaccinesPrimary outcomeBooster dose effectivenessCOVID-19 outcomesPopulation-based cohort studyDose of COVID-19 vaccinePopulation-based cohortPopulation-based cohort of individualsCOVID-19 vaccine dosesSevere COVID-19 outcomesFollow-upCohort studyMRNA-basedVaccine doseCohort of individualsVaccine effectivenessVaccine combinationsDoseLower hazardCohort
2022
Use 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. The 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 effectivenessImmunityVariantsUse of Recently Vaccinated Individuals to Detect Bias in Test-Negative Case–Control Studies of COVID-19 Vaccine Effectiveness
Hitchings MDT, Lewnard JA, Dean NE, Ko AI, Ranzani OT, Andrews JR, Cummings DAT. Use of Recently Vaccinated Individuals to Detect Bias in Test-Negative Case–Control Studies of COVID-19 Vaccine Effectiveness. Epidemiology 2022, 33: 450-456. PMID: 35384900, PMCID: PMC9148635, DOI: 10.1097/ede.0000000000001484.Peer-Reviewed Original ResearchConceptsCOVID-19 vaccine effectivenessVaccine effectivenessNegative control exposureObservational studyControl exposurePhase III trialsTest-negative studiesTest-negative casesVaccine effectiveness estimatesCOVID-19 vaccineDemonstration of efficacyCOVID-19 riskIII trialsUnvaccinated individualsClinical trialsControl studyStudy designEffectiveness estimatesCareful study designUnmeasured confoundingSelection biasTrialsConfoundingExposureIndividuals
2021
Effectiveness of the CoronaVac vaccine in older adults during a gamma variant associated epidemic of covid-19 in Brazil: test negative case-control study
Ranzani OT, Hitchings MDT, Dorion M, D'Agostini TL, de Paula RC, de Paula OFP, Villela EFM, Torres MSS, de Oliveira SB, Schulz W, Almiron M, Said R, de Oliveira RD, Vieira da Silva P, de Araújo WN, Gorinchteyn JC, Andrews JR, Cummings DAT, Ko AI, Croda J. Effectiveness of the CoronaVac vaccine in older adults during a gamma variant associated epidemic of covid-19 in Brazil: test negative case-control study. The BMJ 2021, 374: n2015. PMID: 34417194, PMCID: PMC8377801, DOI: 10.1136/bmj.n2015.Peer-Reviewed Original ResearchConceptsSymptomatic COVID-19Negative case-control studyCase-control studyHospital admissionVaccine effectivenessSecond doseDose regimenElderly populationCOVID-19Reverse transcription polymerase chain reaction testingTranscription polymerase chain reaction testingPolymerase chain reaction testingGamma variantInactivated whole virus vaccineAdjusted vaccine effectivenessTest-negative controlsWhole virus vaccineCOVID-19 statusCOVID-19 symptomsYounger age groupsMunicipality of residenceSARS-CoV-2RT-PCR testSelf-reported raceCoronaVac vaccine