Antispike IgG antibody decay after immunisation with fractional versus full booster doses of COVID-19 vaccines: a 6-month longitudinal analysis of the FRACT-COV trial in Brazil
Verruck J, Puga M, de Oliveira R, da Silva P, Charu V, Hedlin H, Lu D, Zhang A, Ritter V, Shaw B, Rosser J, Seidman J, Carter A, Qamar F, Luby S, Garret D, Croda J. Antispike IgG antibody decay after immunisation with fractional versus full booster doses of COVID-19 vaccines: a 6-month longitudinal analysis of the FRACT-COV trial in Brazil. BMJ Public Health 2025, 3: e002331. PMID: 40620571, PMCID: PMC12228459, DOI: 10.1136/bmjph-2024-002331.Peer-Reviewed Original ResearchDose of BNT162b2Fractionated dosesFollow-up visitIgG antibody levelsFollow-upFull doseAntibody levelsAntibody titresDays of follow-upDays post-booster vaccinationBaseline antibody titresClinically protective levelsFollow-up periodHealthy adultsDose of COVID-19 vaccineDays post-boosterBooster dose of BNT162b2Post-booster vaccinationFull-doseBooster doseIgG levelsAZD1222Post-boosterBNT162b2High antibody titresImmunogenicity and reactogenicity of fractional vs. full booster doses of COVID-19 vaccines: a non-inferiority, randomised, double-blind, phase IV clinical trial in Brazil
Puga M, de Oliveira R, da Silva P, Charu V, Hedlin H, Lu D, Zhang A, Shaw B, Rosser J, Seidman J, Carter A, Qamar F, Luby S, Garrett D, Croda J. Immunogenicity and reactogenicity of fractional vs. full booster doses of COVID-19 vaccines: a non-inferiority, randomised, double-blind, phase IV clinical trial in Brazil. The Lancet Regional Health - Americas 2025, 44: 101031. PMID: 40083966, PMCID: PMC11904515, DOI: 10.1016/j.lana.2025.101031.Peer-Reviewed Original ResearchDose of BNT162b2Fractionated dosesNon-inferiorityNon-inferiority thresholdSeroresponse ratesDouble-blindBooster vaccinationAdverse eventsSystemic adverse eventsPhase IV clinical trialBaseline antibody levelsIV clinical trialDose of COVID-19 vaccineDose of vaccineNon-inferiority studyReduced side effectsAdministering booster vaccinationResource-limited settingsBinding IgG antibodiesImmunocompetent adultsStudy vaccineDose boosterTreatment armsParallel-groupBooster dose
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