biostudies-literatureShaw RHMedical Research CouncilNational Institute for Health Research (NIHR)1049-1060https://www.ebi.ac.uk/biostudies/studies/S-EPMC9179150biostudies-literatureUnknown10(11)<h4>Background</h4>Priming COVID-19 vaccine schedules have been deployed at variable intervals globally, which might influence immune persistence and the relative importance of third-dose booster programmes. Here, we report exploratory analyses from the Com-COV trial, assessing the effect of 4-week versus 12-week priming intervals on reactogenicity and the persistence of immune response up to 6 months after homologous and heterologous priming schedules using the vaccines BNT162b2 (tozinameran, Pfizer/BioNTech) and ChAdOx1 nCoV-19 (AstraZeneca).<h4>Methods</h4>Com-COV was a participant-masked, randomised immunogenicity trial. For these exploratory analyses, we used the trial's general cohort, in which adults aged 50 years or older were randomly assigned to four homologous and four heterologThe Lancet. Respiratory medicineEffect of priming interval on reactogenicity, peak immunological response, and waning after homologous and heterologous COVID-19 vaccine schedules: exploratory analyses of Com-COV, a randomised control trial.PMC9179150MR/N013204/1NF-SI-0617-10010NIHR201409MR/N026993/1Ferreira DMNguyen-Van-Tam JSWalker LLYao XLWarren SRampling THowe EGMujadidi YFTurner PJOkenyi EHeath PTCharlton SHultin CRicamara MBrown CHMaelin FBula MClutterbuck EASingh NLazarus RHughes ECom-COV Study GroupHill HBartholomew JYee Ting NYShaw RHLambe TPresland LRoyal SFinn ASan Francisco Ramos AScreaton GRGreen CANaker KRamasamy MNNoristani RAndrews NJLibri VVarkonyi-Clifford SSaich SQureshi EDesai ABelton SProvstgaard-Morys SHorswill SKellett Wright JKFyles FFaust SNWhittley SGreenland MOldfield NJLong FCarson ADejnirattisai WRamsay MRead RCBurhan HDi Maso CCameron JCWhite RLiu XSnape MDGaliza EPCrook RHammersley DTurner NHallis BPlested ELDinesh TCollins AMMead GStuart ASVRobinson HRiaz TMunro APSGhulam Farooq MTurner DPJAdams KGokani KMorey ERVichos IWilliams RLAley PKPenciu FDfalseEffect of priming interval on reactogenicity, peak immunological response, and waning after homologous and heterologous COVID-19 vaccine schedules: exploratory analyses of Com-COV, a randomised control trial.<h4>Background</h4>Priming COVID-19 vaccine schedules have been deployed at variable intervals globally, which might influence immune persistence and the relative importance of third-dose booster programmes. Here, we report exploratory analyses from the Com-COV trial, assessing the effect of 4-week versus 12-week priming intervals on reactogenicity and the persistence of immune response up to 6 months after homologous and heterologous priming schedules using the vaccines BNT162b2 (tozinameran, Pfizer/BioNTech) and ChAdOx1 nCoV-19 (AstraZeneca).<h4>Methods</h4>Com-COV was a participant-masked, randomised immunogenicity trial. For these exploratory analyses, we used the trial's general cohort, in which adults aged 50 years or older were randomly assigned to four homologous and four heterolog2022-01-01T00:00:00Z2022 Nov2026-05-09T15:11:56.052Z2024-10-15T13:35:11.769ZS-EPMC91791503569007610.1016/S2213-2600(22)00163-1