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Single-dose administration and the influence of the timing of the booster dose on immunogenicity and efficacy of ChAdOx1 nCoV-19 (AZD1222) vaccine: a pooled analysis of four randomised trials.

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cam.depositDate2022-02-23
cam.issuedOnline2021-02-19
dc.contributor.authorVoysey, Merryn
dc.contributor.authorCosta Clemens, Sue Ann
dc.contributor.authorMadhi, Shabir A
dc.contributor.authorWeckx, Lily Y
dc.contributor.authorFolegatti, Pedro M
dc.contributor.authorAley, Parvinder K
dc.contributor.authorAngus, Brian
dc.contributor.authorBaillie, Vicky L
dc.contributor.authorBarnabas, Shaun L
dc.contributor.authorBhorat, Qasim E
dc.contributor.authorBibi, Sagida
dc.contributor.authorBriner, Carmen
dc.contributor.authorCicconi, Paola
dc.contributor.authorClutterbuck, Elizabeth A
dc.contributor.authorCollins, Andrea M
dc.contributor.authorCutland, Clare L
dc.contributor.authorDarton, Thomas C
dc.contributor.authorDheda, Keertan
dc.contributor.authorDold, Christina
dc.contributor.authorDuncan, Christopher JA
dc.contributor.authorEmary, Katherine RW
dc.contributor.authorEwer, Katie J
dc.contributor.authorFlaxman, Amy
dc.contributor.authorFairlie, Lee
dc.contributor.authorFaust, Saul N
dc.contributor.authorFeng, Shuo
dc.contributor.authorFerreira, Daniela M
dc.contributor.authorFinn, Adam
dc.contributor.authorGaliza, Eva
dc.contributor.authorGoodman, Anna L
dc.contributor.authorGreen, Catherine M
dc.contributor.authorGreen, Christopher A
dc.contributor.authorGreenland, Melanie
dc.contributor.authorHill, Catherine
dc.contributor.authorHill, Helen C
dc.contributor.authorHirsch, Ian
dc.contributor.authorIzu, Alane
dc.contributor.authorJenkin, Daniel
dc.contributor.authorJoe, Carina CD
dc.contributor.authorKerridge, Simon
dc.contributor.authorKoen, Anthonet
dc.contributor.authorKwatra, Gaurav
dc.contributor.authorLazarus, Rajeka
dc.contributor.authorLibri, Vincenzo
dc.contributor.authorLillie, Patrick J
dc.contributor.authorMarchevsky, Natalie G
dc.contributor.authorMarshall, Richard P
dc.contributor.authorMendes, Ana VA
dc.contributor.authorMilan, Eveline P
dc.contributor.authorMinassian, Angela M
dc.contributor.authorMcGregor, Alastair
dc.contributor.authorMujadidi, Yama F
dc.contributor.authorNana, Anusha
dc.contributor.authorPadayachee, Sherman D
dc.contributor.authorPhillips, Daniel J
dc.contributor.authorPittella, Ana
dc.contributor.authorPlested, Emma
dc.contributor.authorPollock, Katrina M
dc.contributor.authorRamasamy, Maheshi N
dc.contributor.authorRitchie, Adam J
dc.contributor.authorRobinson, Hannah
dc.contributor.authorSchwarzbold, Alexandre V
dc.contributor.authorSmith, Andrew
dc.contributor.authorSong, Rinn
dc.contributor.authorSnape, Matthew D
dc.contributor.authorSprinz, Eduardo
dc.contributor.authorSutherland, Rebecca K
dc.contributor.authorThomson, Emma C
dc.contributor.authorTörök, M Estée
dc.contributor.authorToshner, Mark
dc.contributor.authorTurner, David PJ
dc.contributor.authorVekemans, Johan
dc.contributor.authorVillafana, Tonya L
dc.contributor.authorWhite, Thomas
dc.contributor.authorWilliams, Christopher J
dc.contributor.authorDouglas, Alexander D
dc.contributor.authorHill, Adrian VS
dc.contributor.authorLambe, Teresa
dc.contributor.authorGilbert, Sarah C
dc.contributor.authorPollard, Andrew J
dc.contributor.authorOxford COVID Vaccine Trial Group
dc.contributor.orcidToshner, Mark [0000-0002-3969-6143]
dc.date.accessioned2022-02-25T00:30:13Z
dc.date.available2022-02-25T00:30:13Z
dc.date.issued2021-03-06
dc.date.updated2022-02-23T14:06:33Z
dc.description.abstractBACKGROUND: The ChAdOx1 nCoV-19 (AZD1222) vaccine has been approved for emergency use by the UK regulatory authority, Medicines and Healthcare products Regulatory Agency, with a regimen of two standard doses given with an interval of 4-12 weeks. The planned roll-out in the UK will involve vaccinating people in high-risk categories with their first dose immediately, and delivering the second dose 12 weeks later. Here, we provide both a further prespecified pooled analysis of trials of ChAdOx1 nCoV-19 and exploratory analyses of the impact on immunogenicity and efficacy of extending the interval between priming and booster doses. In addition, we show the immunogenicity and protection afforded by the first dose, before a booster dose has been offered. METHODS: We present data from three single-blind randomised controlled trials-one phase 1/2 study in the UK (COV001), one phase 2/3 study in the UK (COV002), and a phase 3 study in Brazil (COV003)-and one double-blind phase 1/2 study in South Africa (COV005). As previously described, individuals 18 years and older were randomly assigned 1:1 to receive two standard doses of ChAdOx1 nCoV-19 (5 × 1010 viral particles) or a control vaccine or saline placebo. In the UK trial, a subset of participants received a lower dose (2·2 × 1010 viral particles) of the ChAdOx1 nCoV-19 for the first dose. The primary outcome was virologically confirmed symptomatic COVID-19 disease, defined as a nucleic acid amplification test (NAAT)-positive swab combined with at least one qualifying symptom (fever ≥37·8°C, cough, shortness of breath, or anosmia or ageusia) more than 14 days after the second dose. Secondary efficacy analyses included cases occuring at least 22 days after the first dose. Antibody responses measured by immunoassay and by pseudovirus neutralisation were exploratory outcomes. All cases of COVID-19 with a NAAT-positive swab were adjudicated for inclusion in the analysis by a masked independent endpoint review committee. The primary analysis included all participants who were SARS-CoV-2 N protein seronegative at baseline, had had at least 14 days of follow-up after the second dose, and had no evidence of previous SARS-CoV-2 infection from NAAT swabs. Safety was assessed in all participants who received at least one dose. The four trials are registered at ISRCTN89951424 (COV003) and ClinicalTrials.gov, NCT04324606 (COV001), NCT04400838 (COV002), and NCT04444674 (COV005). FINDINGS: Between April 23 and Dec 6, 2020, 24 422 participants were recruited and vaccinated across the four studies, of whom 17 178 were included in the primary analysis (8597 receiving ChAdOx1 nCoV-19 and 8581 receiving control vaccine). The data cutoff for these analyses was Dec 7, 2020. 332 NAAT-positive infections met the primary endpoint of symptomatic infection more than 14 days after the second dose. Overall vaccine efficacy more than 14 days after the second dose was 66·7% (95% CI 57·4-74·0), with 84 (1·0%) cases in the 8597 participants in the ChAdOx1 nCoV-19 group and 248 (2·9%) in the 8581 participants in the control group. There were no hospital admissions for COVID-19 in the ChAdOx1 nCoV-19 group after the initial 21-day exclusion period, and 15 in the control group. 108 (0·9%) of 12 282 participants in the ChAdOx1 nCoV-19 group and 127 (1·1%) of 11 962 participants in the control group had serious adverse events. There were seven deaths considered unrelated to vaccination (two in the ChAdOx1 nCov-19 group and five in the control group), including one COVID-19-related death in one participant in the control group. Exploratory analyses showed that vaccine efficacy after a single standard dose of vaccine from day 22 to day 90 after vaccination was 76·0% (59·3-85·9). Our modelling analysis indicated that protection did not wane during this initial 3-month period. Similarly, antibody levels were maintained during this period with minimal waning by day 90 (geometric mean ratio [GMR] 0·66 [95% CI 0·59-0·74]). In the participants who received two standard doses, after the second dose, efficacy was higher in those with a longer prime-boost interval (vaccine efficacy 81·3% [95% CI 60·3-91·2] at ≥12 weeks) than in those with a short interval (vaccine efficacy 55·1% [33·0-69·9] at <6 weeks). These observations are supported by immunogenicity data that showed binding antibody responses more than two-fold higher after an interval of 12 or more weeks compared with an interval of less than 6 weeks in those who were aged 18-55 years (GMR 2·32 [2·01-2·68]). INTERPRETATION: The results of this primary analysis of two doses of ChAdOx1 nCoV-19 were consistent with those seen in the interim analysis of the trials and confirm that the vaccine is efficacious, with results varying by dose interval in exploratory analyses. A 3-month dose interval might have advantages over a programme with a short dose interval for roll-out of a pandemic vaccine to protect the largest number of individuals in the population as early as possible when supplies are scarce, while also improving protection after receiving a second dose. FUNDING: UK Research and Innovation, National Institutes of Health Research (NIHR), The Coalition for Epidemic Preparedness Innovations, the Bill & Melinda Gates Foundation, the Lemann Foundation, Rede D'Or, the Brava and Telles Foundation, NIHR Oxford Biomedical Research Centre, Thames Valley and South Midland's NIHR Clinical Research Network, and AstraZeneca.
dc.format.mediumPrint-Electronic
dc.identifier.doi10.17863/CAM.81856
dc.identifier.eissn1474-547X
dc.identifier.issn0140-6736
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/334441
dc.language.isoeng
dc.publisherElsevier BV
dc.publisher.departmentDepartment of Medicine
dc.publisher.urlhttp://dx.doi.org/10.1016/s0140-6736(21)00432-3
dc.rightsAttribution 4.0 International
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.subjectAdolescent
dc.subjectAdult
dc.subjectAged
dc.subjectAntibody Formation
dc.subjectAsymptomatic Infections
dc.subjectCOVID-19
dc.subjectCOVID-19 Vaccines
dc.subjectChAdOx1 nCoV-19
dc.subjectHumans
dc.subjectImmunization Schedule
dc.subjectImmunization, Secondary
dc.subjectMiddle Aged
dc.subjectRandomized Controlled Trials as Topic
dc.subjectSARS-CoV-2
dc.subjectYoung Adult
dc.titleSingle-dose administration and the influence of the timing of the booster dose on immunogenicity and efficacy of ChAdOx1 nCoV-19 (AZD1222) vaccine: a pooled analysis of four randomised trials.
dc.typeArticle
dcterms.dateAccepted2021-02-11
prism.endingPage891
prism.issueIdentifier10277
prism.publicationDate2021
prism.publicationNameLancet
prism.startingPage881
prism.volume397
pubs.licence-display-nameApollo Repository Deposit Licence Agreement
pubs.licence-identifierapollo-deposit-licence-2-1
rioxxterms.typeJournal Article/Review
rioxxterms.versionVoR
rioxxterms.versionofrecord10.1016/S0140-6736(21)00432-3

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