2025
The validity of test-negative design for assessment of typhoid conjugate vaccine protection: comparison of estimates by different study designs using data from a cluster-randomised controlled trial
Feng S, Zhang Y, Khanam F, Voysey M, Pitzer V, Qadri F, Clemens J, Pollard A, Liu X. The validity of test-negative design for assessment of typhoid conjugate vaccine protection: comparison of estimates by different study designs using data from a cluster-randomised controlled trial. The Lancet Global Health 2025, 13: e1122-e1131. PMID: 40252689, PMCID: PMC12095117, DOI: 10.1016/s2214-109x(25)00056-7.Peer-Reviewed Original ResearchConceptsTyphoid Conjugate VaccineCluster randomised controlled trialJapanese encephalitis vaccineAge-eligible childrenCohort designTest-negative controlsStudy designTyphoid feverVaccine effectivenessHealth care seeking behaviorNon-vaccineesIncreased riskBlood culture-confirmed typhoid feverSalmonella enterica serotype TyphiCase-control study designNon-typhoidal infectionsVaccine protectionBlood culture specimensExperimental study designMiddle-income countriesObservational study designPublic health challengeChildren aged 9 monthsIncreased risk of typhoid feverRisk of typhoid fever
2024
5-year vaccine protection following a single dose of Vi-tetanus toxoid conjugate vaccine in Bangladeshi children (TyVOID): a cluster randomised trial
Qadri F, Khanam F, Zhang Y, Biswas P, Voysey M, Mujadidi Y, Kelly S, Bhuiyan A, Rajib N, Hossen I, Rahman N, Islam S, Pitzer V, Kim Y, Clemens J, Pollard A, Liu X. 5-year vaccine protection following a single dose of Vi-tetanus toxoid conjugate vaccine in Bangladeshi children (TyVOID): a cluster randomised trial. The Lancet 2024, 404: 1419-1429. PMID: 39396349, DOI: 10.1016/s0140-6736(24)01494-6.Peer-Reviewed Original ResearchConceptsTyphoid Conjugate VaccineJapanese encephalitis vaccineVaccine effectivenessRandomised controlled trialsConjugate vaccineFollow-upTyphoid feverControlled TrialsVaccine protectionChildren aged 9 monthsIncreased risk of typhoid feverAnti-Vi IgGRisk of typhoid feverVaccine efficacy dataTest-negative designAged 9 monthsUnvaccinated individualsHigh-burden countriesIncidence rate ratiosAnalyses of vaccine effectivenessSingle-doseSingle doseDecay of antibodiesSubgroup analysisBooster dose
2023
Assessment of vaccine herd protection in a cluster-randomised trial of Vi conjugate vaccine against typhoid fever: results of further analysis
Khanam F, Kim D, Liu X, Voysey M, Pitzer V, Zaman K, Pollard A, Qadri F, Clemens J. Assessment of vaccine herd protection in a cluster-randomised trial of Vi conjugate vaccine against typhoid fever: results of further analysis. EClinicalMedicine 2023, 58: 101925. PMID: 37090439, PMCID: PMC10114505, DOI: 10.1016/j.eclinm.2023.101925.Peer-Reviewed Original ResearchVaccine herd protectionCluster-randomised trialHerd protectionTransmission of typhoidVi-TTTyphoid feverChildren 9 monthsVi-tetanus toxoidMonths of followJapanese encephalitis vaccineYears of ageTotal vaccine effectivenessUrban Bangladeshi childrenVaccine effectivenessEncephalitis vaccineStudy populationBangladeshi childrenTreatment centersCluster residentsIndirect effectivenessMelinda Gates FoundationTrialsVaccineAnalysis of subpopulationsFever
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