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1.
Cell Reports Medicine ; : 100882, 2022.
Article in English | ScienceDirect | ID: covidwho-2159932

ABSTRACT

Summary The nasal mucosa is an important initial site of host defense against SARS-CoV-2 infection. However, intramuscularly administered vaccines typically do not achieve high antibody titers in nasal mucosa. We measure anti-SARS-CoV-2 spike IgG and IgA in nasal epithelial lining fluid (NELF) following intramuscular vaccination of 3,058 participants from the immunogenicity substudy of NCT04516746: A phase 3, double-blind, placebo-controlled study of AZD1222 vaccination. IgG is detected in NELF collected 14 days following first AZD1222 vaccination. IgG levels increase with a second vaccination and exceed pre-existing levels in baseline-SARS-CoV-2-seropositive participants. Nasal IgG responses are durable and display strong correlations with serum IgG, suggesting serum-to-NELF transudation. AZD1222 induces short-lived increases to pre-existing nasal IgA levels in baseline-seropositive vaccinees. Vaccinees display a robust recall IgG response upon breakthrough infection with overall magnitudes unaffected by time between vaccination and illness. Mucosal responses correlate with reduced viral loads and shorter durations of viral shedding in saliva.

2.
Clin Infect Dis ; 2022 Nov 22.
Article in English | MEDLINE | ID: covidwho-2135003

ABSTRACT

BACKGROUND: We report primary results of a phase 3 trial of AZD7442 (tixagevimab/cilgavimab) for post-exposure prophylaxis to prevent symptomatic coronavirus disease 2019 (COVID-19). METHODS: Adults without prior SARS-CoV-2 infection or COVID-19 vaccination were enrolled within 8 days of exposure to a SARS-CoV-2-infected individual and randomized 2:1 to a single 300-mg AZD7442 dose (one 1.5-mL intramuscular injection each of tixagevimab and cilgavimab consecutively) or placebo. Primary endpoints were safety and first post-dose SARS-CoV-2 reverse-transcription-polymerase-chain-reaction (RT-PCR)-positive symptomatic COVID-19 event before day 183. RESULTS: 1121 participants were randomized and dosed (mean age 46 years; 49% females; AZD7442, n=749; placebo, n=372). Median (range) follow-up was 49 (5-115) and 48 (20-113) days for AZD7442 and placebo, respectively. Adverse events occurred in 162/749 (21.6%) and 111/372 (29.8%) participants with AZD7442 and placebo, respectively, mostly mild/moderate. RT-PCR-positive symptomatic COVID-19 occurred in 23/749 (3.1%) and 17/372 (4.6%) AZD7442- and placebo-treated participants, respectively (relative risk reduction 33.3%; 95% confidence interval [CI] -25.9 to 64.7; P=.21). In predefined subgroup analyses of 1073 (96%) participants who were SARS-CoV-2 RT-PCR-negative (n=974 [87%]) or missing an RT-PCR result (n=99 [9%]) at baseline, AZD7442 reduced RT-PCR-positive symptomatic COVID-19 by 73.2% (95% CI 27.1 to 90.1) versus placebo. CONCLUSIONS: This study did not meet the primary efficacy endpoint of post-exposure prevention of symptomatic COVID-19 with AZD7442 versus placebo. However, predefined analysis of participants who were SARS-CoV-2 RT-PCR-negative or missing an RT-PCR result at baseline support a role for AZD7442 in preventing symptomatic COVID-19.

3.
EBioMedicine ; 85: 104298, 2022 Nov.
Article in English | MEDLINE | ID: covidwho-2061074

ABSTRACT

BACKGROUND: Intranasal vaccination may induce protective local and systemic immune responses against respiratory pathogens. A number of intranasal SARS-CoV-2 vaccine candidates have achieved protection in pre-clinical challenge models, including ChAdOx1 nCoV-19 (AZD1222, University of Oxford / AstraZeneca). METHODS: We performed a single-centre open-label Phase I clinical trial of intranasal vaccination with ChAdOx1 nCoV-19 in healthy adults, using the existing formulation produced for intramuscular administration. Thirty SARS-CoV-2 vaccine-naïve participants were allocated to receive 5 × 109 viral particles (VP, n=6), 2 × 1010 VP (n=12), or 5 × 1010 VP (n=12). Fourteen received second intranasal doses 28 days later. A further 12 received non-study intramuscular mRNA SARS-CoV-2 vaccination between study days 22 and 46. To investigate intranasal ChAdOx1 nCoV-19 as a booster, six participants who had previously received two intramuscular doses of ChAdOx1 nCoV-19 and six who had received two intramuscular doses of BNT162b2 (Pfizer / BioNTech) were given a single intranasal dose of 5 × 1010 VP of ChAdOx1 nCoV-19. Objectives were to assess safety (primary) and mucosal antibody responses (secondary). FINDINGS: Reactogenicity was mild or moderate. Antigen-specific mucosal antibody responses to intranasal vaccination were detectable in a minority of participants, rarely exceeding levels seen after SARS-CoV-2 infection. Systemic responses to intranasal vaccination were typically weaker than after intramuscular vaccination with ChAdOx1 nCoV-19. Antigen-specific mucosal antibody was detectable in participants who received an intramuscular mRNA vaccine after intranasal vaccination. Seven participants developed symptomatic SARS-CoV-2 infection. INTERPRETATION: This formulation of intranasal ChAdOx1 nCoV-19 showed an acceptable tolerability profile but induced neither a consistent mucosal antibody response nor a strong systemic response. FUNDING: AstraZeneca.


Subject(s)
COVID-19 , Viral Vaccines , Adult , Humans , Adenoviridae/genetics , Antibodies, Viral , BNT162 Vaccine , ChAdOx1 nCoV-19 , COVID-19/prevention & control , COVID-19 Vaccines/adverse effects , SARS-CoV-2 , Vaccination/adverse effects
4.
J Clin Invest ; 132(18)2022 09 15.
Article in English | MEDLINE | ID: covidwho-2029589

ABSTRACT

BackgroundWe report updated safety, efficacy, and immunogenicity of AZD1222 (ChAdOx1 nCoV-19) from an ongoing phase 3 trial.MethodsAdults at increased risk of SARS-CoV-2 infection were randomized (2:1), stratified by age, to receive 2 doses of AZD1222 or placebo. The primary efficacy end point was confirmed SARS-CoV-2 reverse-transcriptase PCR-positive (RT-PCR-positive) symptomatic COVID-19 at 15 or more days after a second dose in baseline SARS-CoV-2-seronegative participants. The 21,634 and 10,816 participants were randomized to AZD1222 and placebo, respectively.FindingsData cutoff for this analysis was July 30, 2021; median follow-up from second dose was 78 and 71 days for the double-blind period (censoring at unblinding or nonstudy COVID-19 vaccination) and 201 and 82 days for the period to nonstudy COVID-19 vaccination (regardless of unblinding) in the AZD1222 and placebo groups, respectively. For the primary efficacy end point in the double-blind period (141 and 184 events; incidence rates: 39.2 and 118.8 per 1,000 person years), vaccine efficacy was 67.0% (P < 0.001). In the period to nonstudy COVID-19 vaccination, incidence of events remained consistently low and stable through 6 months in the AZD1222 group; for the primary efficacy end point (328 and 219 events; incidence rates: 36.4, 108.4) and severe/critical disease (5 and 13 events; incidence rates: 0.6, 6.4), respective vaccine efficacy estimates were 65.1% and 92.1%. AZD1222 elicited humoral immune responses over time, with waning at day 180. No emergent safety issues were seen.ConclusionAZD1222 is safe and well tolerated, demonstrating durable protection and immunogenicity with median follow-up (AZD1222 group) of 6 months.Trial registrationClinicalTrials.gov NCT04516746.FundingAstraZeneca; US government.


Subject(s)
COVID-19 Vaccines , COVID-19 , COVID-19/prevention & control , COVID-19 Vaccines/adverse effects , ChAdOx1 nCoV-19 , Humans , SARS-CoV-2 , Vaccination
5.
Microbiol Spectr ; 10(5): e0103422, 2022 Oct 26.
Article in English | MEDLINE | ID: covidwho-2001787

ABSTRACT

AZD7442, a combination of two long-acting monoclonal antibodies (tixagevimab [AZD8895] and cilgavimab [AZD1061]), has been authorized for the prevention and treatment of coronavirus disease 2019 (COVID-19). The rapid emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants requires methods capable of quickly characterizing resistance to AZD7442. To support AZD7442 resistance monitoring, a biolayer interferometry (BLI) assay was developed to screen the binding of tixagevimab and cilgavimab to SARS-CoV-2 spike proteins to reduce the number of viral variants for neutralization susceptibility verification. Six spike variants were chosen to assess the assay's performance: four with decreased affinity for tixagevimab (F486S:D614G and F486W:D614G proteins) or cilgavimab (S494L:D614G and K444R:D614G proteins) and two reference proteins (wild-type HexaPro and D614G protein). Equilibrium dissociation constant (KD) values from each spike protein were used to determine shifts in binding affinity. The assay's precision, range, linearity, and limits of quantitation were established. Qualification acceptance criteria determined whether the assay was fit for purpose. By bypassing protein purification, the BLI assay provided increased screening throughput. Although limited correlation between pseudotype neutralization and BLI data (50% inhibitory concentration versus KD) was observed for full immunoglobulins (IgGs), the correlations for antibody fragments (Fabs) were stronger and reflected a better comparison of antibody binding kinetics with neutralization potency. Therefore, despite strong assay performance characteristics, the use of full IgGs limited the screening utility of the assay; however, the Fab approach warrants further exploration as a rapid, high-throughput variant-screening method for future resistance-monitoring programs. IMPORTANCE SARS-CoV-2 variants harbor multiple substitutions in their spike trimers, potentially leading to breakthrough infections and clinical resistance to immune therapies. For this reason, a BLI assay was developed and qualified to evaluate the reliability of screening SARS-CoV-2 spike trimer variants against anti-SARS-CoV-2 monoclonal antibodies (MAbs) tixagevimab and cilgavimab, the components of AZD7442, prior to in vitro pseudovirus neutralization susceptibility verification testing. The assay bypasses protein purification with rapid assessment of the binding affinity of each MAb for each recombinant protein, potentially providing an efficient preliminary selection step, thus allowing a reduced testing burden in the more technically complex viral neutralization assays. Despite precise and specific measures, an avidity effect associated with MAb binding to the trimer confounded correlation with neutralization potency, negating the assay's utility as a surrogate for neutralizing antibody potency. Improved correlation with Fabs suggests that assay optimization could overcome any avidity limitation, warranting further exploration to support future resistance-monitoring programs.


Subject(s)
COVID-19 , Spike Glycoprotein, Coronavirus , Humans , SARS-CoV-2/genetics , Reproducibility of Results , COVID-19/drug therapy , Antibodies, Monoclonal/therapeutic use , Antibodies, Neutralizing , Antibodies, Viral , Interferometry , Immunoglobulin Fragments , Recombinant Proteins
6.
N Engl J Med ; 386(23): 2188-2200, 2022 06 09.
Article in English | MEDLINE | ID: covidwho-1805743

ABSTRACT

BACKGROUND: The monoclonal-antibody combination AZD7442 is composed of tixagevimab and cilgavimab, two neutralizing antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that have an extended half-life and have been shown to have prophylactic and therapeutic effects in animal models. Pharmacokinetic data in humans indicate that AZD7442 has an extended half-life of approximately 90 days. METHODS: In an ongoing phase 3 trial, we enrolled adults (≥18 years of age) who had an increased risk of an inadequate response to vaccination against coronavirus disease 2019 (Covid-19), an increased risk of exposure to SARS-CoV-2, or both. Participants were randomly assigned in a 2:1 ratio to receive a single dose (two consecutive intramuscular injections, one containing tixagevimab and the other containing cilgavimab) of either 300 mg of AZD7442 or saline placebo, and they were followed for up to 183 days in the primary analysis. The primary safety end point was the incidence of adverse events after a single dose of AZD7442. The primary efficacy end point was symptomatic Covid-19 (SARS-CoV-2 infection confirmed by means of reverse-transcriptase-polymerase-chain-reaction assay) occurring after administration of AZD7442 or placebo and on or before day 183. RESULTS: A total of 5197 participants underwent randomization and received one dose of AZD7442 or placebo (3460 in the AZD7442 group and 1737 in the placebo group). The primary analysis was conducted after 30% of the participants had become aware of their randomized assignment. In total, 1221 of 3461 participants (35.3%) in the AZD7442 group and 593 of 1736 participants (34.2%) in the placebo group reported having at least one adverse event, most of which were mild or moderate in severity. Symptomatic Covid-19 occurred in 8 of 3441 participants (0.2%) in the AZD7442 group and in 17 of 1731 participants (1.0%) in the placebo group (relative risk reduction, 76.7%; 95% confidence interval [CI], 46.0 to 90.0; P<0.001); extended follow-up at a median of 6 months showed a relative risk reduction of 82.8% (95% CI, 65.8 to 91.4). Five cases of severe or critical Covid-19 and two Covid-19-related deaths occurred, all in the placebo group. CONCLUSIONS: A single dose of AZD7442 had efficacy for the prevention of Covid-19, without evident safety concerns. (Funded by AstraZeneca and the U.S. government; PROVENT ClinicalTrials.gov number, NCT04625725.).


Subject(s)
Antiviral Agents , COVID-19 , Adult , Antibodies, Monoclonal/administration & dosage , Antibodies, Monoclonal/therapeutic use , Antibodies, Neutralizing/administration & dosage , Antibodies, Neutralizing/therapeutic use , Antiviral Agents/administration & dosage , Antiviral Agents/therapeutic use , COVID-19/prevention & control , Double-Blind Method , Drug Combinations , Humans , Injections, Intramuscular , SARS-CoV-2
7.
Clin Transl Immunology ; 11(4): e1385, 2022.
Article in English | MEDLINE | ID: covidwho-1802162

ABSTRACT

Objectives: Robust, quantitative serology assays are required to accurately measure antibody levels following vaccination and natural infection. We present validation of a quantitative, multiplex, SARS-CoV-2, electrochemiluminescent (ECL) serology assay; show correlation with two established SARS-CoV-2 immunoassays; and present calibration results for two SARS-CoV-2 reference standards. Methods: Precision, dilutional linearity, ruggedness, analytical sensitivity and specificity were evaluated. Clinical sensitivity and specificity were assessed using serum from prepandemic and SARS-CoV-2 polymerase chain reaction (PCR)-positive patient samples. Assay concordance to the established Roche Elecsys® Anti-SARS-CoV-2 immunoassay and a live-virus microneutralisation (MN) assay was evaluated. Results: Standard curves demonstrated the assay can quantify SARS-CoV-2 antibody levels over a broad range. Assay precision (10.2-15.1% variability), dilutional linearity (≤ 1.16-fold bias per 10-fold increase in dilution), ruggedness (0.89-1.18 overall fold difference), relative accuracy (107-118%) and robust selectivity (102-104%) were demonstrated. Analytical sensitivity was 7, 13 and 7 arbitrary units mL-1 for SARS-CoV-2 spike (S), receptor-binding domain (RBD) and nucleocapsid (N) antigens, respectively. For all antigens, analytical specificity was > 90% and clinical specificity was 99.0%. Clinical sensitivities for S, RBD and N antigens were 100%, 98.8% and 84.9%, respectively. Comparison with the Elecsys® immunoassay showed ≥ 87.7% agreement and linear correlation (Pearson r of 0.85, P < 0.0001) relative to the MN assay. Conversion factors for the WHO International Standard and Meso Scale Discovery® Reference Standard are presented. Conclusions: The multiplex SARS-CoV-2 ECL serology assay is suitable for efficient, reproducible measurement of antibodies to SARS-CoV-2 antigens in human sera, supporting its use in clinical trials and sero-epidemiology studies.

8.
Sci Transl Med ; 14(635): eabl8124, 2022 03 09.
Article in English | MEDLINE | ID: covidwho-1736022

ABSTRACT

Despite the success of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines, there remains a need for more prevention and treatment options for individuals remaining at risk of coronavirus disease 2019 (COVID-19). Monoclonal antibodies (mAbs) against the viral spike protein have potential to both prevent and treat COVID-19 and reduce the risk of severe disease and death. Here, we describe AZD7442, a combination of two mAbs, AZD8895 (tixagevimab) and AZD1061 (cilgavimab), that simultaneously bind to distinct, nonoverlapping epitopes on the spike protein receptor binding domain to neutralize SARS-CoV-2. Initially isolated from individuals with prior SARS-CoV-2 infection, the two mAbs were designed to extend their half-lives and reduce effector functions. The AZD7442 mAbs individually prevent the spike protein from binding to angiotensin-converting enzyme 2 receptor, blocking virus cell entry, and neutralize all tested SARS-CoV-2 variants of concern. In a nonhuman primate model of SARS-CoV-2 infection, prophylactic AZD7442 administration prevented infection, whereas therapeutic administration accelerated virus clearance from the lung. In an ongoing phase 1 study in healthy participants (NCT04507256), a 300-mg intramuscular injection of AZD7442 provided SARS-CoV-2 serum geometric mean neutralizing titers greater than 10-fold above those of convalescent serum for at least 3 months, which remained threefold above those of convalescent serum at 9 months after AZD7442 administration. About 1 to 2% of serum AZD7442 was detected in nasal mucosa, a site of SARS-CoV-2 infection. Extrapolation of the time course of serum AZD7442 concentration suggests AZD7442 may provide up to 12 months of protection and benefit individuals at high-risk of COVID-19.


Subject(s)
COVID-19 , SARS-CoV-2 , Animals , Antibodies, Monoclonal , Antibodies, Neutralizing , Antibodies, Viral , COVID-19/drug therapy , COVID-19/therapy , Drug Combinations , Half-Life , Humans , Immunization, Passive , Primates , Spike Glycoprotein, Coronavirus
9.
BMC Genomics ; 23(1): 121, 2022 Feb 11.
Article in English | MEDLINE | ID: covidwho-1690976

ABSTRACT

BACKGROUND: More than 2 million SARS-CoV-2 genome sequences have been generated and shared since the start of the COVID-19 pandemic and constitute a vital information source that informs outbreak control, disease surveillance, and public health policy. The Pango dynamic nomenclature is a popular system for classifying and naming genetically-distinct lineages of SARS-CoV-2, including variants of concern, and is based on the analysis of complete or near-complete virus genomes. However, for several reasons, nucleotide sequences may be generated that cover only the spike gene of SARS-CoV-2. It is therefore important to understand how much information about Pango lineage status is contained in spike-only nucleotide sequences. Here we explore how Pango lineages might be reliably designated and assigned to spike-only nucleotide sequences. We survey the genetic diversity of such sequences, and investigate the information they contain about Pango lineage status. RESULTS: Although many lineages, including the main variants of concern, can be identified clearly using spike-only sequences, some spike-only sequences are shared among tens or hundreds of Pango lineages. To facilitate the classification of SARS-CoV-2 lineages using subgenomic sequences we introduce the notion of designating such sequences to a "lineage set", which represents the range of Pango lineages that are consistent with the observed mutations in a given spike sequence. CONCLUSIONS: We find that many lineages, including the main variants-of-concern, can be reliably identified by spike alone and we define lineage-sets to represent the lineage precision that can be achieved using spike-only nucleotide sequences. These data provide a foundation for the development of software tools that can assign newly-generated spike nucleotide sequences to Pango lineage sets.


Subject(s)
COVID-19 , SARS-CoV-2 , Base Sequence , Humans , Mutation , Pandemics , Phylogeny , Spike Glycoprotein, Coronavirus/genetics
10.
EClinicalMedicine ; 42: 101218, 2021 Dec.
Article in English | MEDLINE | ID: covidwho-1540604

ABSTRACT

BACKGROUND: This phase 2/3 immunobridging study evaluated the safety and immunogenicity of the ChAdOx1 nCoV-19 Coronavirus Vaccine (Recombinant) (SII-ChAdOx1 nCoV-19), manufactured in India at the Serum Institute of India Pvt Ltd (SIIPL), following technology transfer from the AstraZeneca. METHODS: This participant-blind, observer-blind study randomised participants 3:1 to SII-ChAdOx1 nCoV-19 or AZD1222 (ChAdOx1 nCoV-19) (immunogenicity/reactogenicity cohort) and 3:1 to SII-ChAdOx1 nCoV-19 or placebo (safety cohort). The study participants were enrolled from 14 hospitals across India between August 25 and October 31, 2020. Two doses of study products were given 4 weeks apart. The primary objectives were to demonstrate non-inferiority of SII-ChAdOx1 nCoV-19 to AZD1222 in terms of geometric mean titre (GMT) ratio of anti-SARS-CoV-2 spike IgG antibodies 28 days after the second dose (defined as lower limit of 95% CI >0·67) and to determine the incidence of serious adverse events (SAEs) causally related to SII-ChAdOx1 nCoV-19. The anti-spike IgG response was assessed using a multiplexed electrochemiluminescence-based immunoassay. Safety follow-up continued until 6 months after first dose. Trial registration: CTRI/2020/08/027170. FINDINGS: 1601 participants were enrolled: 401 to the immunogenicity/reactogenicity cohort and 1200 to the safety cohort. After two doses, seroconversion rates for anti-spike IgG antibodies were more than 98·0% in both the groups. SII-ChAdOx1 nCoV-19 was non-inferior to AZD1222 (GMT ratio 0·98; 95% CI 0·78-1·23). SAEs were reported in ≤ 2·0% participants across the three groups; none were causally related. A total of 34 SARS-CoV-2 infections were reported; of which 6 occurred more than 2 weeks after the second dose; none were severe. INTERPRETATION: SII-ChAdOx1 nCoV-19 has a non-inferior immune response compared to AZD1222 and an acceptable safety/reactogenicity profile. Pharmacovigilance should be maintained to detect any safety signals. FUNDING: SIIPL funded the contract research organisation and laboratory costs, while the site costs were funded by the Indian Council of Medical Research. The study vaccines were supplied by SIIPL and AstraZeneca.

11.
Nat Med ; 27(11): 2032-2040, 2021 11.
Article in English | MEDLINE | ID: covidwho-1526097

ABSTRACT

The global supply of COVID-19 vaccines remains limited. An understanding of the immune response that is predictive of protection could facilitate rapid licensure of new vaccines. Data from a randomized efficacy trial of the ChAdOx1 nCoV-19 (AZD1222) vaccine in the United Kingdom was analyzed to determine the antibody levels associated with protection against SARS-CoV-2. Binding and neutralizing antibodies at 28 days after the second dose were measured in infected and noninfected vaccine recipients. Higher levels of all immune markers were correlated with a reduced risk of symptomatic infection. A vaccine efficacy of 80% against symptomatic infection with majority Alpha (B.1.1.7) variant of SARS-CoV-2 was achieved with 264 (95% CI: 108, 806) binding antibody units (BAU)/ml: and 506 (95% CI: 135, not computed (beyond data range) (NC)) BAU/ml for anti-spike and anti-RBD antibodies, and 26 (95% CI: NC, NC) international unit (IU)/ml and 247 (95% CI: 101, NC) normalized neutralization titers (NF50) for pseudovirus and live-virus neutralization, respectively. Immune markers were not correlated with asymptomatic infections at the 5% significance level. These data can be used to bridge to new populations using validated assays, and allow extrapolation of efficacy estimates to new COVID-19 vaccines.


Subject(s)
COVID-19 Vaccines/therapeutic use , COVID-19/epidemiology , COVID-19/prevention & control , Immunity, Humoral , SARS-CoV-2/immunology , Adolescent , Adult , Aged , Aged, 80 and over , Antibodies, Neutralizing/blood , Antibodies, Viral/blood , Asymptomatic Infections , COVID-19/immunology , COVID-19/pathology , COVID-19 Vaccines/genetics , COVID-19 Vaccines/immunology , Cohort Studies , Female , Humans , Immunization, Secondary , Infection Control/statistics & numerical data , Male , Middle Aged , Patient Acuity , SARS-CoV-2/genetics , Treatment Outcome , United Kingdom/epidemiology , Vaccination , Young Adult
12.
Int J Infect Dis ; 114: 165-174, 2022 Jan.
Article in English | MEDLINE | ID: covidwho-1474621

ABSTRACT

BACKGROUND: Immunogenicity and safety of the AZD1222 (ChAdOx1 nCoV-19) vaccine was evaluated in Japanese adults in an ongoing phase 1/2, randomized, double-blind, parallel-group, placebo-controlled, multi-centre trial (NCT04568031). METHODS: Adults (n=256, age ≥18 years) seronegative for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) were stratified by age into 18-55- (n=128), 56-69- (n=86) and ≥70-year-old cohorts (n=42), and randomized 3:1 to receive AZD1222 or placebo (two intramuscular injections 4 weeks apart). Immunogenicity and safety were coprimary endpoints. Data collected up to Day 57 are reported. RESULTS: Positive seroresponses to SARS-CoV-2 spike and receptor-binding domain antigens were seen in all 174 participants who received two doses of AZD1222. Neutralizing antibody seroresponses were seen in 67.5%, 60.3% and 50.0% of participants receiving AZD1222 aged 18-55, 56-69 and ≥70 years, respectively. Solicited adverse events (AEs) were typically mild/moderate in severity and included pain and tenderness at the injection site, malaise, fatigue, muscle pain and headache. Common unsolicited AEs included pain and tenderness at the injection site, fatigue and elevated body temperature. No vaccine-related serious AEs or deaths were reported. CONCLUSIONS: AZD1222 elicited a strong humoral immune response against SARS-CoV-2, and was well tolerated in Japanese participants, including elderly participants.


Subject(s)
COVID-19 , ChAdOx1 nCoV-19 , Adolescent , Adult , Aged , Antibodies, Neutralizing , Antibodies, Viral , COVID-19 Vaccines , ChAdOx1 nCoV-19/adverse effects , Double-Blind Method , Humans , Japan , Middle Aged , SARS-CoV-2 , Young Adult
13.
N Engl J Med ; 385(25): 2348-2360, 2021 12 16.
Article in English | MEDLINE | ID: covidwho-1442847

ABSTRACT

BACKGROUND: The safety and efficacy of the AZD1222 (ChAdOx1 nCoV-19) vaccine in a large, diverse population at increased risk for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the United States, Chile, and Peru has not been known. METHODS: In this ongoing, double-blind, randomized, placebo-controlled, phase 3 clinical trial, we investigated the safety, vaccine efficacy, and immunogenicity of two doses of AZD1222 as compared with placebo in preventing the onset of symptomatic and severe coronavirus disease 2019 (Covid-19) 15 days or more after the second dose in adults, including older adults, in the United States, Chile, and Peru. RESULTS: A total of 32,451 participants underwent randomization, in a 2:1 ratio, to receive AZD1222 (21,635 participants) or placebo (10,816 participants). AZD1222 was safe, with low incidences of serious and medically attended adverse events and adverse events of special interest; the incidences were similar to those observed in the placebo group. Solicited local and systemic reactions were generally mild or moderate in both groups. Overall estimated vaccine efficacy was 74.0% (95% confidence interval [CI], 65.3 to 80.5; P<0.001) and estimated vaccine efficacy was 83.5% (95% CI, 54.2 to 94.1) in participants 65 years of age or older. High vaccine efficacy was consistent across a range of demographic subgroups. In the fully vaccinated analysis subgroup, no severe or critical symptomatic Covid-19 cases were observed among the 17,662 participants in the AZD1222 group; 8 cases were noted among the 8550 participants in the placebo group (<0.1%). The estimated vaccine efficacy for preventing SARS-CoV-2 infection (nucleocapsid antibody seroconversion) was 64.3% (95% CI, 56.1 to 71.0; P<0.001). SARS-CoV-2 spike protein binding and neutralizing antibodies increased after the first dose and increased further when measured 28 days after the second dose. CONCLUSIONS: AZD1222 was safe and efficacious in preventing symptomatic and severe Covid-19 across diverse populations that included older adults. (Funded by AstraZeneca and others; ClinicalTrials.gov number, NCT04516746.).


Subject(s)
COVID-19/prevention & control , Adolescent , Adult , Aged , Aged, 80 and over , Antibodies, Neutralizing/blood , Antibodies, Viral/blood , COVID-19/epidemiology , Chile/epidemiology , Double-Blind Method , Female , Humans , Immunogenicity, Vaccine , Male , Middle Aged , Peru/epidemiology , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , United States/epidemiology , Young Adult
14.
Sci Transl Med ; 13(620): eabj7211, 2021 Nov 17.
Article in English | MEDLINE | ID: covidwho-1443349

ABSTRACT

AZD1222 (ChAdOx1 nCoV-19), a replication-deficient simian adenovirus­vectored vaccine, has demonstrated safety, efficacy, and immunogenicity against coronavirus disease 2019 in clinical trials and real-world studies. We characterized CD4+ and CD8+ T cell responses induced by AZD1222 vaccination in peripheral blood mononuclear cells from 296 unique vaccine recipients aged 18 to 85 years who enrolled in the phase 2/3 COV002 trial. Total spike protein­specific CD4+ T cell helper type 1 (TH1) and CD8+ T cell responses were increased in AZD1222-vaccinated adults of all ages after two doses of AZD1222. CD4+ TH2 responses after AZD1222 vaccination were not detected. Furthermore, AZD1222-specific TH1 and CD8+ T cells both displayed a high degree of polyfunctionality in all adult age groups. T cell receptor ß (TCRß) sequences from vaccinated participants mapped against TCR sequences known to react to SARS-CoV-2 revealed substantial breadth and depth across the SARS-CoV-2 spike protein for both AZD1222-induced CD4+ and CD8+ T cell responses. Overall, AZD1222 vaccination induced a polyfunctional TH1-dominated T cell response, with broad CD4+ and CD8+ T cell coverage across the SARS-CoV-2 spike protein.


Subject(s)
COVID-19 , Spike Glycoprotein, Coronavirus , COVID-19 Vaccines , Humans , Receptors, Antigen, T-Cell , SARS-CoV-2 , Vaccination
15.
N Engl J Med ; 384(20): 1885-1898, 2021 05 20.
Article in English | MEDLINE | ID: covidwho-1135713

ABSTRACT

BACKGROUND: Assessment of the safety and efficacy of vaccines against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in different populations is essential, as is investigation of the efficacy of the vaccines against emerging SARS-CoV-2 variants of concern, including the B.1.351 (501Y.V2) variant first identified in South Africa. METHODS: We conducted a multicenter, double-blind, randomized, controlled trial to assess the safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222) in people not infected with the human immunodeficiency virus (HIV) in South Africa. Participants 18 to less than 65 years of age were assigned in a 1:1 ratio to receive two doses of vaccine containing 5×1010 viral particles or placebo (0.9% sodium chloride solution) 21 to 35 days apart. Serum samples obtained from 25 participants after the second dose were tested by pseudovirus and live-virus neutralization assays against the original D614G virus and the B.1.351 variant. The primary end points were safety and efficacy of the vaccine against laboratory-confirmed symptomatic coronavirus 2019 illness (Covid-19) more than 14 days after the second dose. RESULTS: Between June 24 and November 9, 2020, we enrolled 2026 HIV-negative adults (median age, 30 years); 1010 and 1011 participants received at least one dose of placebo or vaccine, respectively. Both the pseudovirus and the live-virus neutralization assays showed greater resistance to the B.1.351 variant in serum samples obtained from vaccine recipients than in samples from placebo recipients. In the primary end-point analysis, mild-to-moderate Covid-19 developed in 23 of 717 placebo recipients (3.2%) and in 19 of 750 vaccine recipients (2.5%), for an efficacy of 21.9% (95% confidence interval [CI], -49.9 to 59.8). Among the 42 participants with Covid-19, 39 cases (95.1% of 41 with sequencing data) were caused by the B.1.351 variant; vaccine efficacy against this variant, analyzed as a secondary end point, was 10.4% (95% CI, -76.8 to 54.8). The incidence of serious adverse events was balanced between the vaccine and placebo groups. CONCLUSIONS: A two-dose regimen of the ChAdOx1 nCoV-19 vaccine did not show protection against mild-to-moderate Covid-19 due to the B.1.351 variant. (Funded by the Bill and Melinda Gates Foundation and others; ClinicalTrials.gov number, NCT04444674; Pan African Clinical Trials Registry number, PACTR202006922165132).


Subject(s)
Antibodies, Neutralizing/blood , COVID-19 Vaccines/immunology , COVID-19/prevention & control , Immunogenicity, Vaccine , SARS-CoV-2 , Adenoviridae , Adolescent , Adult , Antibodies, Neutralizing/physiology , COVID-19/epidemiology , COVID-19/immunology , COVID-19 Serological Testing , COVID-19 Vaccines/administration & dosage , COVID-19 Vaccines/adverse effects , Double-Blind Method , Humans , Middle Aged , South Africa , T-Lymphocytes/physiology , Treatment Failure , Vaccine Potency , Young Adult
16.
Lancet ; 396(10267): 1979-1993, 2021 12 19.
Article in English | MEDLINE | ID: covidwho-933547

ABSTRACT

BACKGROUND: Older adults (aged ≥70 years) are at increased risk of severe disease and death if they develop COVID-19 and are therefore a priority for immunisation should an efficacious vaccine be developed. Immunogenicity of vaccines is often worse in older adults as a result of immunosenescence. We have reported the immunogenicity of a novel chimpanzee adenovirus-vectored vaccine, ChAdOx1 nCoV-19 (AZD1222), in young adults, and now describe the safety and immunogenicity of this vaccine in a wider range of participants, including adults aged 70 years and older. METHODS: In this report of the phase 2 component of a single-blind, randomised, controlled, phase 2/3 trial (COV002), healthy adults aged 18 years and older were enrolled at two UK clinical research facilities, in an age-escalation manner, into 18-55 years, 56-69 years, and 70 years and older immunogenicity subgroups. Participants were eligible if they did not have severe or uncontrolled medical comorbidities or a high frailty score (if aged ≥65 years). First, participants were recruited to a low-dose cohort, and within each age group, participants were randomly assigned to receive either intramuscular ChAdOx1 nCoV-19 (2·2 × 1010 virus particles) or a control vaccine, MenACWY, using block randomisation and stratified by age and dose group and study site, using the following ratios: in the 18-55 years group, 1:1 to either two doses of ChAdOx1 nCoV-19 or two doses of MenACWY; in the 56-69 years group, 3:1:3:1 to one dose of ChAdOx1 nCoV-19, one dose of MenACWY, two doses of ChAdOx1 nCoV-19, or two doses of MenACWY; and in the 70 years and older, 5:1:5:1 to one dose of ChAdOx1 nCoV-19, one dose of MenACWY, two doses of ChAdOx1 nCoV-19, or two doses of MenACWY. Prime-booster regimens were given 28 days apart. Participants were then recruited to the standard-dose cohort (3·5-6·5 × 1010 virus particles of ChAdOx1 nCoV-19) and the same randomisation procedures were followed, except the 18-55 years group was assigned in a 5:1 ratio to two doses of ChAdOx1 nCoV-19 or two doses of MenACWY. Participants and investigators, but not staff administering the vaccine, were masked to vaccine allocation. The specific objectives of this report were to assess the safety and humoral and cellular immunogenicity of a single-dose and two-dose schedule in adults older than 55 years. Humoral responses at baseline and after each vaccination until 1 year after the booster were assessed using an in-house standardised ELISA, a multiplex immunoassay, and a live severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) microneutralisation assay (MNA80). Cellular responses were assessed using an ex-vivo IFN-γ enzyme-linked immunospot assay. The coprimary outcomes of the trial were efficacy, as measured by the number of cases of symptomatic, virologically confirmed COVID-19, and safety, as measured by the occurrence of serious adverse events. Analyses were by group allocation in participants who received the vaccine. Here, we report the preliminary findings on safety, reactogenicity, and cellular and humoral immune responses. This study is ongoing and is registered with ClinicalTrials.gov, NCT04400838, and ISRCTN, 15281137. FINDINGS: Between May 30 and Aug 8, 2020, 560 participants were enrolled: 160 aged 18-55 years (100 assigned to ChAdOx1 nCoV-19, 60 assigned to MenACWY), 160 aged 56-69 years (120 assigned to ChAdOx1 nCoV-19: 40 assigned to MenACWY), and 240 aged 70 years and older (200 assigned to ChAdOx1 nCoV-19: 40 assigned to MenACWY). Seven participants did not receive the boost dose of their assigned two-dose regimen, one participant received the incorrect vaccine, and three were excluded from immunogenicity analyses due to incorrectly labelled samples. 280 (50%) of 552 analysable participants were female. Local and systemic reactions were more common in participants given ChAdOx1 nCoV-19 than in those given the control vaccine, and similar in nature to those previously reported (injection-site pain, feeling feverish, muscle ache, headache), but were less common in older adults (aged ≥56 years) than younger adults. In those receiving two standard doses of ChAdOx1 nCoV-19, after the prime vaccination local reactions were reported in 43 (88%) of 49 participants in the 18-55 years group, 22 (73%) of 30 in the 56-69 years group, and 30 (61%) of 49 in the 70 years and older group, and systemic reactions in 42 (86%) participants in the 18-55 years group, 23 (77%) in the 56-69 years group, and 32 (65%) in the 70 years and older group. As of Oct 26, 2020, 13 serious adverse events occurred during the study period, none of which were considered to be related to either study vaccine. In participants who received two doses of vaccine, median anti-spike SARS-CoV-2 IgG responses 28 days after the boost dose were similar across the three age cohorts (standard-dose groups: 18-55 years, 20 713 arbitrary units [AU]/mL [IQR 13 898-33 550], n=39; 56-69 years, 16 170 AU/mL [10 233-40 353], n=26; and ≥70 years 17 561 AU/mL [9705-37 796], n=47; p=0·68). Neutralising antibody titres after a boost dose were similar across all age groups (median MNA80 at day 42 in the standard-dose groups: 18-55 years, 193 [IQR 113-238], n=39; 56-69 years, 144 [119-347], n=20; and ≥70 years, 161 [73-323], n=47; p=0·40). By 14 days after the boost dose, 208 (>99%) of 209 boosted participants had neutralising antibody responses. T-cell responses peaked at day 14 after a single standard dose of ChAdOx1 nCoV-19 (18-55 years: median 1187 spot-forming cells [SFCs] per million peripheral blood mononuclear cells [IQR 841-2428], n=24; 56-69 years: 797 SFCs [383-1817], n=29; and ≥70 years: 977 SFCs [458-1914], n=48). INTERPRETATION: ChAdOx1 nCoV-19 appears to be better tolerated in older adults than in younger adults and has similar immunogenicity across all age groups after a boost dose. Further assessment of the efficacy of this vaccine is warranted in all age groups and individuals with comorbidities. 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.


Subject(s)
COVID-19 Vaccines/administration & dosage , Immunogenicity, Vaccine , Adolescent , Adult , Age Factors , Aged , Aged, 80 and over , COVID-19/prevention & control , COVID-19 Vaccines/adverse effects , COVID-19 Vaccines/pharmacology , Female , Humans , Immunization, Secondary/adverse effects , Immunoglobulin G/blood , Immunoglobulin G/drug effects , Male , Middle Aged , SARS-CoV-2/drug effects , Single-Blind Method , Young Adult
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