ABSTRACT
Background: COVID-19 vaccine supply shortages are causing concerns about compromised immunity in some countries as the interval between first and second dose extends. Conversely, countries with no supply constraints are considering administering a third dose. We assessed the persistence of immunogenicity after a single dose, the immunity after an extended interval between the first and second dose of ChAdOx1 nCoV-19(AZD1222), and the response to a third dose as a late booster. Methods: Volunteers aged 18-55 years who were enrolled in a Phase 1/2 or Phase 2/3 clinical trial of ChAdOx1 nCoV-19 and had received either a single dose or two doses of 5×10 10 viral particles were invited back for vaccination. Reactogenicity and immunogenicity of a delayed second dose or a third dose are reported here.Findings: Antibody titres after a single dose and measured on d362 remain higher than the titres measured on d0 (62.61 EU; 95% CI 47.43-82.64 vs 1 EU 95% CI 1-16). 30 participants received a late second dose of ChAdOx1 nCoV-19 (median 44 weeks after first dose), antibody titres were higher in those with a longer interval between first and second dose (median EU for 8-12, 15-25, and 44-46 weeks were 923 [IQR 525-1764], 1860 [IQR 917-4934] and 3738 [IQR 1824-6625] respectively). 90 participants received a third dose and antibody titres were significantly higher following a third dose (FRNT50 612 [IQR 351-920]) when compared with the response 28 days after a second dose (FRNT 50 319 [IQR 176-591]. T-cell responses were also boosted after a third dose. Reactogenicity after a late second dose or a third dose was lower than reactogenicity after a first dose.Interpretation: A longer delay before the second dose of ChAdOx1 nCoV-19 leads to an increased antibody titre after the second dose. A third dose of ChAdOx1 nCoV-19 induces antibodies to a level that correlate with high efficacy after second dose and boosts T-cell responses.Funding: UK Research and Innovation (MC_PC_19055), Engineering and Physical Sciences Research Council (EP/R013756/1), National Institute for Health Research (COV19 OxfordVacc-01), Coalition for Epidemic Preparedness Innovations (Outbreak Response To Novel Coronavirus (COVID-19)), National Institute for Health Research Oxford Biomedical Research Centre (BRC4 Vaccines Theme), Thames Valley and South Midland’s NIHR Clinical Research Network, and AstraZeneca. The views expressed in this publication are those of the authors and not necessarily those of the NIHR or the UK Department of Health and Social Care.Declaration of Interest: Oxford University has entered into a partnership with AstraZeneca for further development of ChAdOx1 nCoV-19. AstraZeneca reviewed the data from the study and the final manuscript before submission, but the authors retained editorial control. SCG and AVSH are cofounders of and shareholders in Vaccitech (collaborators in the early development of this vaccine candidate) and named as inventors on a patent covering use of ChAdOx1-vectored vaccines (PCT/GB2012/000467) and a patent application covering this SARS-CoV-2 vaccine (SCG only). TL is named as an inventor on a patent covering use of ChAdOx1-vectored vaccines (PCT/GB2012/000467) and was a consultant to Vaccitech. PMF is a consultant to Vaccitech. AJP is Chair of the UK Department of Health and Social Care’s JCVI, but does not participate in policy advice on coronavirus vaccines, and is a member of the WHO Strategic Advisory Group of Experts (SAGE). AJP is a NIHR Senior Investigator.Ethical Approval: In the UK, the COV001 and COV002 studies were approved by the South Central Berkshire Research Ethics Committee (COV001 reference 20/SC/0145, March 23, 2020; and COV002 reference 20/SC/0179; conditional approval April 8, full approval April 19, 2020).
Subject(s)
COVID-19ABSTRACT
Background Emerging evidence shows the substantial real-world impact of authorised vaccines against COVID-19 and provides insight into the potential role of vaccines in curbing the pandemic. However, there remains uncertainty about the efficacy of vaccines against different variants of the virus. Here we assessed efficacy of ChAdOx1 nCoV-19 (AZD1222) against lineages of SARS-CoV-2 circulating in Brazil from June 2020 until early 2021. Methods Participants aged 18 and above were enrolled into a randomised phase 3 trial of ChAdOx1 nCoV-19 vaccine against symptomatic SARS-CoV-2 infection. Participants received two doses of ChAdOx1 nCoV-19 or control (1st dose: Men ACWY vaccine, 2nd dose: normal saline). Nasopharyngeal and oropharyngeal swabbing was performed if participants developed symptoms of COVID-19 (cough, shortness of breath, fever >37.8°C, ageusia, anosmia). Swabs were tested by nucleic acid amplification (NAAT) for SARS-CoV-2, sequenced, and viral load determined. For those samples where a genotype could not be ascertained from sequencing, allele specific PCR was performed. The efficacy analysis included symptomatic COVID-19 in seronegative participants with a NAAT positive swab more than 14 days after a second dose of vaccine. Participants were unblinded after the vaccine was authorised for use, and the control participants offered vaccination. Infections occurring after unblinding were excluded from analysis. Vaccine efficacy was calculated as 100% x (1 – relative risk (RR)), where RR was estimated from a robust Poisson model. The trial is registered at ISRCTN89951424. Findings 9433 participants were eligible for inclusion in the pre-specified primary efficacy population, having reached more than 14 days after a second dose of ChAdOx1 nCoV-19, of whom 307 were NAAT+, in this post-hoc analysis. From June 2020 to February 2021, the two most frequently identified lineages were P.2 (N=153) and B.1.1.28 (N=49). P.1 emerged during the study (N=18) but became dominant only after study unblinding. Viral loads were highest amongst those with P.1 infection. Vaccine efficacy (VE) for B.1.1.33 (88.2%, 95%CI 5, 99), B.1.1.28 (73%, 95% CI, 46, 86), P.2 (69% 95% CI, 55, 78) and P.1 (64%, 95% CI, -2, 87) was estimated. In participants who had received two doses of vaccine, one COVID-19 hospitalisation occurred in the ChAdOx1 nCoV-19 group and 18 in the control group, with VE against hospitalisation 95% (95% CI 61, 99). There were 2 COVID-19 deaths in the control group and none in the vaccine group. Interpretation ChAdOx1 nCoV-19 provides high efficacy against hospitalisation, severe disease and death from COVID-19 in Brazil and there is strong evidence of protection being maintained against P.2, despite the presence of the spike protein mutation E484K. Real world effectiveness studies are ongoing in Brazil to further establish protection against P.1 and other emerging variants.
Subject(s)
Dyspnea , Fever , Olfaction Disorders , Death , COVID-19 , AgeusiaABSTRACT
Background: The ChAdOx1 nCoV-19 (AZD1222) vaccine is immunogenic and protects against COVID-19. However, data on vaccine immunogenicity are needed for the 40 million people living with HIV (PWH), who may have less functional immunity and more associated co-morbidities than the general population. Methods: Between the 5th and 24th November 2020, 54 adults with HIV, aged 18-55 years, were enrolled into a single arm open label vaccination study within the protocol of the larger phase 2/3 COV002 trial. A prime-boost regimen of ChAdOx1 nCoV-19, with two doses (5 × 1010 vp) was given 4-6 weeks apart. All participants were on antiretroviral therapy (ART) with undetectable plasma HIV viral loads and CD4+ T cell counts >350 cells/µl at enrolment. Data were captured on adverse events. Humoral responses were measured by anti-spike IgG ELISA and antibody-mediated live virus neutralisation. Cell-mediated immune responses were measured by ex-vivo interferon-γ enzyme-linked immunospot assay (ELISpot) and T cell proliferation. All outcomes were compared with a HIV uninfected group from the main COV002 study.Findings: 54 participants with HIV (median age 42.5 years (IQR 37.2-49.8)) received two doses of ChAdOx1 nCoV-19. Median CD4+ T cell count at enrolment was 694 cells/µl (IQR 562-864). Results are reported for 56 days of follow-up. Local and systemic reactions occurring during the first 7 days after prime vaccination included pain at the injection site (49%), fatigue (47%), headache (47%), malaise (34%), chills (23%), and muscle or (36%) joint pain (9%), the frequencies of which were similar to the HIV-negative participants. There were no serious adverse events. Anti-spike IgG responses by ELISA peaked at Day 42 (median 1440 ELISA units, IQR 704-2728) and were sustained out to Day 56. There was no correlation with CD4+ T cell count or age and the magnitude of the anti-spike IgG response at Day 56 (P>0.05 for both). ELISpot and T cell proliferative responses peaked between Day 14 and 28 after prime and were sustained through to Day 56. When compared to participants without HIV there was no statistical difference in magnitude or persistence of SARS-CoV-2 spike-specific humoral or cellular responses (P>0.05 for all analyses).Interpretation: In this study of PWH, vaccination with ChAdOx1 nCoV-19 was well tolerated and there was no difference in humoral and cell-mediated immune responses compared to an adult cohort without HIV who received the same vaccination regime. Trial Registration: Trial Registration number is NCT04400838. Funding: UK Research and Innovation, National Institutes for Health Research (NIHR), Coalition for Epidemic Preparedness Innovations, NIHR Oxford Biomedical Research Centre, Thames Valley and South Midlands NIHR Clinical Research Network, and AstraZeneca. The views expressed are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social Care.Declaration of Interest: Oxford University has entered into a partnership with AstraZeneca for further development of ChAdOx1 nCoV-19 (AZD1222). AstraZeneca reviewed the data from the study and the final manuscript before 474 submission, but the authors retained editorial control. SCG is cofounder of Vaccitech (a collaborator in the early development of this vaccine candidate) and named as an inventor on a patent covering use of ChAdOx1-vectored vaccines (PCT/GB2012/000467) and a patent application covering this SARS-CoV-2 vaccine. TL is named as an inventor on a patent application covering this SARS-CoV-2 vaccine and was consultant to Vaccitech. PMF is a consultant to Vaccitech. AJP is Chair of the UK Department of Health and Social Care’s JCVI, but does not participate in policy advice on coronavirus vaccines, and is a member of the WHO Strategic Advisory Group of Experts (SAGE). AVSH is a cofounder of and consultant to Vaccitech and is named as an inventor on a patent covering design and use of ChAdOx1-vectored vaccines (PCT/GB2012/000467).Ethical Approval: Written informed consent was obtained from all participants, and the trial was done in accordance with the principles of the Declaration of Helsinki and Good Clinical Practice. This study was approved in the UK by the Medicines and Healthcare products Regulatory Agency (reference 21584/0424/001-0001) and the South Central Berkshire Research Ethics Committee (reference 20/SC/0145). Vaccine use was authorised by Genetically Modified Organisms Safety Committees at each participating site.
Subject(s)
HIV Infections , COVID-19 , Hemoglobin SC DiseaseABSTRACT
Background: The ChAdOx1 nCoV-19 (AZD1222) vaccine has been approved for emergency use by the UK regulatory authority, MHRA, with a regimen of two standard doses given with an interval of between 4 and 12 weeks. The planned rollout 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 phase III efficacy trials of ChAdOx1 nCoV-19 in the United Kingdom and Brazil, and phase I/II clinical trials in the UK and South Africa, against symptomatic disease caused by SARS-CoV-2. The data cut-off date for these analyses was 7th December 2020. The accumulated cases of COVID-19 disease at this cut-off date exceeds the number required for a pre-specified final analysis, which is also presented. As previously described, individuals over 18 years of age were randomised 1:1 to receive two standard doses (SD) of ChAdOx1 nCoV-19 (5x1010 viral particles) or a control vaccine/saline placebo. In the UK trial efficacy cohort a subset of participants received a lower dose (LD, 2.2x1010 viral particles) of the ChAdOx1 nCoV-19 for the first dose. All cases with a nucleic acid amplification test (NAAT) were adjudicated for inclusion in the analysis, by a blinded independent endpoint review committee. Studies are registered at ISRCTN89951424 and ClinicalTrials.gov; NCT04324606, NCT04400838, and NCT04444674.Findings: 17,177 baseline seronegative trial participants were eligible for inclusion in the efficacy analysis, 8948 in the UK, 6753 in Brazil and 1476 in South Africa, with 619 documented NAAT +ve infections of which 332 met the primary endpoint of symptomatic infection >14 days post dose 2.The primary analysis of overall vaccine efficacy >14 days after the second dose including LD/SD and SD/SD groups, based on the prespecified criteria was 66.7% (57.4%, 74.0%). There were no hospitalisations in the ChAdOx1 nCoV-19 group after the initial 21 day exclusion period, and 15 in the control group.Vaccine efficacy after a single standard dose of vaccine from day 22 to day 90 post vaccination was 76% (59%, 86%), and modelled 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 day (GMR 0.66, 95% CI 0.59, 0.74).In the SD/SD group, after the second dose, efficacy was higher with a longer prime-boost interval: VE 82.4% 95%CI 62.7%, 91.7% at 12+ weeks, compared with VE 54.9%, 95%CI 32.7%, 69.7% at <6 weeks. These observations are supported by immunogenicity data which showed binding antibody responses more than 2-fold higher after an interval of 12 or more weeks compared with and interval of less than 6 weeks GMR 2.19 (2.12, 2.26) in those who were 18-55 years of age.Interpretation: ChAdOx1 nCoV-19 vaccination programmes aimed at vaccinating a large proportion of the population with a single dose, with a second dose given after a 3 month period is an effective strategy for reducing disease, and may be the optimal for rollout of a pandemic vaccine when supplies are limited in the short term.Trial Registration: Studies are registered at ISRCTN89951424 and ClinicalTrials.gov; NCT04324606, NCT04400838, and NCT04444674.Funding: UKRI, NIHR, CEPI, 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 Astra Zeneca.Conflict of Interest: Oxford University has entered into a partnership with Astra Zeneca for further development of ChAdOx1 nCoV-19. SCG is co-founder of Vaccitech (collaborators in the early development of this vaccine candidate) and named as an inventor on a patent covering use of ChAdOx1-vectored vaccines and a patent application covering this SARS-CoV-2 vaccine. TL is named as aninventor on a patent application covering this SARS-CoV-2 vaccine and was a consultant to Vaccitech for an unrelated project. PMF is a consultant to Vaccitech. AJP is Chair of UK Dept.Health and Social Care’s (DHSC) Joint Committee on Vaccination & Immunisation (JCVI), but does not participate in discussions on COVID-19 vaccines, and is a member of the WHO’sSAGE. AJP and SNF are NIHR Senior Investigator. The views expressed in this article do not necessarily represent the views of DHSC, JCVI, NIHR or WHO. AVSH reports personal feesfrom Vaccitech, outside the submitted work and has a patent on ChAdOx1 licensed to Vaccitech, and may benefit from royalty income to the University of Oxford from sales of this vaccine by AstraZeneca and sublicensees. MS reports grants from NIHR, non-financial support fromAstraZeneca, during the conduct of the study; grants from Janssen, grants fromGlaxoSmithKline, grants from Medimmune, grants from Novavax, grants and non-financialsupport from Pfizer, grants from MCM, outside the submitted work. CG reports personal fees from the Duke Human Vaccine Institute, outside of the submitted work. SNF reports grants from Janssen and Valneva, outside the submitted work. ADD reports grants and personal fees from AstraZeneca, outside of the submitted work. In addition, ADD has a patent manufacturingprocess for ChAdOx vectors with royalties paid to AstraZeneca, and a patent ChAdOx2 vector with royalties paid to AstraZeneca. The other authors declare no competing interests.