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1.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-335278

ABSTRACT

Low-volume antibody assays can be used to track SARS-CoV-2 infection rates in settings where active testing for virus is limited and remote sampling is optimal. We developed 12 ELISAs detecting total or antibody isotypes to SARS-CoV-2 nucleocapsid, spike protein or its receptor binding domain (RBD), 3 anti-RBD isotype specific luciferase immunoprecipitation system (LIPS) assays and a novel Spike-RBD bridging LIPS total-antibody assay. We utilised pre-pandemic (n=984) and confirmed/suspected recent COVID-19 sera taken pre-vaccination rollout in 2020 (n=269). Assays measuring total antibody discriminated best between pre-pandemic and COVID-19 sera and were selected for diagnostic evaluation. In the blind evaluation, two of these assays (Spike Pan ELISA and Spike-RBD Bridging LIPS assay) demonstrated >97% specificity and >92% sensitivity for samples from COVID- 19 patients taken >21 days post symptom onset or PCR test. These assays offered better sensitivity for the detection of COVID-19 cases than a commercial assay which requires 100-fold larger serum volumes. This study demonstrates that low-volume in- house antibody assays can provide good diagnostic performance, and highlights the importance of using well-characterised samples and controls for all stages of assay development and evaluation. These cost-effective assays may be particularly useful for seroprevalence studies in low and middle-income countries.

2.
Relph, Katharine A.; Russell, Clark D.; Fairfield, Cameron J.; Turtle, Lance, de Silva, Thushan I.; Siggins, Matthew K.; Drake, Thomas M.; Thwaites, Ryan S.; Abrams, Simon, Moore, Shona C.; Hardwick, Hayley E.; Oosthuyzen, Wilna, Harrison, Ewen M.; Docherty, Annemarie B.; Openshaw, Peter J. M.; Baillie, J. Kenneth, Semple, Malcolm G.; Ho, Antonia, Baillie, J. Kenneth, Semple, Malcolm G.; Openshaw, Peter J. M.; Carson, Gail, Alex, Beatrice, Bach, Benjamin, Barclay, Wendy S.; Bogaert, Debby, Chand, Meera, Cooke, Graham S.; Docherty, Annemarie B.; Dunning, Jake, Filipe, Ana da Silva, Fletcher, Tom, Green, Christopher A.; Harrison, Ewen M.; Hiscox, Julian A.; Ho, Antonia Ying Wai, Horby, Peter W.; Ijaz, Samreen, Khoo, Saye, Klenerman, Paul, Law, Andrew, Lim, Wei Shen, Mentzer, Alexander J.; Merson, Laura, Meynert, Alison M.; Noursadeghi, Mahdad, Moore, Shona C.; Palmarini, Massimo, Paxton, William A.; Pollakis, Georgios, Price, Nicholas, Rambaut, Andrew, Robertson, David L.; Russell, Clark D.; Sancho-Shimizu, Vanessa, Scott, Janet T.; de Silva, Thushan, Sigfrid, Louise, Solomon, Tom, Sriskandan, Shiranee, Stuart, David, Summers, Charlotte, Tedder, Richard S.; Thomson, Emma C.; Roger Thompson, A. A.; Thwaites, Ryan S.; Turtle, Lance C. W.; Gupta, Rishi K.; Zambon, Maria, Hardwick, Hayley, Donohue, Chloe, Lyons, Ruth, Griffiths, Fiona, Oosthuyzen, Wilna, Norman, Lisa, Pius, Riinu, Drake, Thomas M.; Fairfield, Cameron J.; Knight, Stephen R.; McLean, Kenneth A.; Murphy, Derek, Shaw, Catherine A.; Dalton, Jo, Girvan, Michelle, Saviciute, Egle, Roberts, Stephanie, Harrison, Janet, Marsh, Laura, Connor, Marie, Halpin, Sophie, Jackson, Clare, Gamble, Carrol, Leeming, Gary, Law, Andrew, Wham, Murray, Clohisey, Sara, Hendry, Ross, Scott-Brown, James, Greenhalf, William, Shaw, Victoria, McDonald, Sara, Keating, Seán, Ahmed, Katie A.; Armstrong, Jane A.; Ashworth, Milton, Asiimwe, Innocent G.; Bakshi, Siddharth, Barlow, Samantha L.; Booth, Laura, Brennan, Benjamin, Bullock, Katie, Catterall, Benjamin W. A.; Clark, Jordan J.; Clarke, Emily A.; Cole, Sarah, Cooper, Louise, Cox, Helen, Davis, Christopher, Dincarslan, Oslem, Dunn, Chris, Dyer, Philip, Elliott, Angela, Evans, Anthony, Finch, Lorna, Fisher, Lewis W. S.; Foster, Terry, Garcia-Dorival, Isabel, Greenhalf, William, Gunning, Philip, Hartley, Catherine, Jensen, Rebecca L.; Jones, Christopher B.; Jones, Trevor R.; Khandaker, Shadia, King, Katharine, Kiy, Robyn T.; Koukorava, Chrysa, Lake, Annette, Lant, Suzannah, Latawiec, Diane, Lavelle-Langham, Lara, Lefteri, Daniella, Lett, Lauren, Livoti, Lucia A.; Mancini, Maria, McDonald, Sarah, McEvoy, Laurence, McLauchlan, John, Metelmann, Soeren, Miah, Nahida S.; Middleton, Joanna, Mitchell, Joyce, Moore, Shona C.; Murphy, Ellen G.; Penrice-Randal, Rebekah, Pilgrim, Jack, Prince, Tessa, Reynolds, Will, Matthew Ridley, P.; Sales, Debby, Shaw, Victoria E.; Shears, Rebecca K.; Small, Benjamin, Subramaniam, Krishanthi S.; Szemiel, Agnieska, Taggart, Aislynn, Tanianis-Hughes, Jolanta, Thomas, Jordan, Trochu, Erwan, van Tonder, Libby, Wilcock, Eve, Eunice Zhang, J.; Flaherty, Lisa, Maziere, Nicole, Cass, Emily, Doce Carracedo, Alejandra, Carlucci, Nicola, Holmes, Anthony, Massey, Hannah, Murphy, Lee, Wrobel, Nicola, McCafferty, Sarah, Morrice, Kirstie, MacLean, Alan, Adeniji, Kayode, Agranoff, Daniel, Agwuh, Ken, Ail, Dhiraj, Aldera, Erin L.; Alegria, Ana, Angus, Brian, Ashish, Abdul, Atkinson, Dougal, Bari, Shahedal, Barlow, Gavin, Barnass, Stella, Barrett, Nicholas, Bassford, Christopher, Basude, Sneha, Baxter, David, Beadsworth, Michael, Bernatoniene, Jolanta, Berridge, John, Best, Nicola, Bothma, Pieter, Chadwick, David, Brittain-Long, Robin, Bulteel, Naomi, Burden, Tom, Burtenshaw, Andrew, Caruth, Vikki, Chadwick, David, Chambler, Duncan, Chee, Nigel, Child, Jenny, Chukkambotla, Srikanth, Clark, Tom, Collini, Paul, Cosgrove, Catherine, Cupitt, Jason, Cutino-Moguel, Maria-Teresa, Dark, Paul, Dawson, Chris, Dervisevic, Samir, Donnison, Phil, Douthwaite, Sam, DuRand, Ingrid, Dushianthan, Ahilanadan, Dyer, Tristan, Evans, Cariad, Eziefula, Chi, Fegan, Christopher, Finn, Adam, Fullerton, Duncan, Garg, Sanjeev, Garg, Sanjeev, Garg, Atul, Gkrania-Klotsas, Effrossyni, Godden, Jo, Goldsmith, Arthur, Graham, Clive, Hardy, Elaine, Hartshorn, Stuart, Harvey, Daniel, Havalda, Peter, Hawcutt, Daniel B.; Hobrok, Maria, Hodgson, Luke, Hormis, Anil, Jacobs, Michael, Jain, Susan, Jennings, Paul, Kaliappan, Agilan, Kasipandian, Vidya, Kegg, Stephen, Kelsey, Michael, Kendall, Jason, Kerrison, Caroline, Kerslake, Ian, Koch, Oliver, Koduri, Gouri, Koshy, George, Laha, Shondipon, Laird, Steven, Larkin, Susan, Leiner, Tamas, Lillie, Patrick, Limb, James, Linnett, Vanessa, Little, Jeff, Lyttle, Mark, MacMahon, Michael, MacNaughton, Emily, Mankregod, Ravish, Masson, Huw, Matovu, Elijah, McCullough, Katherine, McEwen, Ruth, Meda, Manjula, Mills, Gary, Minton, Jane, Mirfenderesky, Mariyam, Mohandas, Kavya, Mok, Quen, Moon, James, Moore, Elinoor, Morgan, Patrick, Morris, Craig, Mortimore, Katherine, Moses, Samuel, Mpenge, Mbiye, Mulla, Rohinton, Murphy, Michael, Nagel, Megan, Nagarajan, Thapas, Nelson, Mark, O’Shea, Matthew K.; Otahal, Igor, Ostermann, Marlies, Pais, Mark, Panchatsharam, Selva, Papakonstantinou, Danai, Paraiso, Hassan, Patel, Brij, Pattison, Natalie, Pepperell, Justin, Peters, Mark, Phull, Mandeep, Pintus, Stefania, Pooni, Jagtur Singh, Post, Frank, Price, David, Prout, Rachel, Rae, Nikolas, Reschreiter, Henrik, Reynolds, Tim, Richardson, Neil, Roberts, Mark, Roberts, Devender, Rose, Alistair, Rousseau, Guy, Ryan, Brendan, Saluja, Taranprit, Shah, Aarti, Shanmuga, Prad, Sharma, Anil, Shawcross, Anna, Sizer, Jeremy, Shankar-Hari, Manu, Smith, Richard, Snelson, Catherine, Spittle, Nick, Staines, Nikki, Stambach, Tom, Stewart, Richard, Subudhi, Pradeep, Szakmany, Tamas, Tatham, Kate, Thomas, Jo, Thompson, Chris, Thompson, Robert, Tridente, Ascanio, Tupper-Carey, Darell, Twagira, Mary, Ustianowski, Andrew, Vallotton, Nick, Vincent-Smith, Lisa, Visuvanathan, Shico, Vuylsteke, Alan, Waddy, Sam, Wake, Rachel, Walden, Andrew, Welters, Ingeborg, Whitehouse, Tony, Whittaker, Paul, Whittington, Ashley, Papineni, Padmasayee, Wijesinghe, Meme, Williams, Martin, Wilson, Lawrence, Cole, Sarah, Winchester, Stephen, Wiselka, Martin, Wolverson, Adam, Wootton, Daniel G.; Workman, Andrew, Yates, Bryan, Young, Peter.
Open Forum Infectious Diseases ; 9(5), 2022.
Article in English | PMC | ID: covidwho-1821760

ABSTRACT

Admission procalcitonin measurements and microbiology results were available for 1040 hospitalized adults with coronavirus disease 2019 (from 48 902 included in the International Severe Acute Respiratory and Emerging Infections Consortium World Health Organization Clinical Characterisation Protocol UK study). Although procalcitonin was higher in bacterial coinfection, this was neither clinically significant (median [IQR], 0.33 [0.11–1.70] ng/mL vs 0.24 [0.10–0.90] ng/mL) nor diagnostically useful (area under the receiver operating characteristic curve, 0.56 [95% confidence interval, .51–.60]).

3.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-334149

ABSTRACT

Saliva is easily obtainable non-invasively and potentially suitable for detecting both current and previous SARS-CoV-2 infection. We established 6 standardised enzyme linked immunosorbent assays (ELISA) capable of detecting IgA and IgG antibodies to whole SARS-CoV-2 spike protein, to its receptor binding domain region and to nucleocapsid protein in saliva. In test accuracy (n=320), we found that spike IgG performed best (ROC AUC: 95.0%, 92.8-97.3%), followed by spike IgA (ROC AUC: 89.9%, 86.5-93.2%) for discriminating between pre-pandemic and post COVID-19 saliva samples. Using machine learning, diagnostic performance was improved when a combination of tests was used. As expected, salivary IgA was poorly correlated with serum, indicating an oral mucosal response whereas salivary IgG responses were predictive of those in serum. When deployed to 20 household outbreaks undergoing Delta and Omicron infection, antibody responses were heterogeneous but remained a reliable indicator of recent infection. Intriguingly, unvaccinated children showed evidence of exposure almost exclusively through specific IgA responses in the absence of evidence of viral infection. We have provided robust standardisation, evaluation, and field-testing of salivary antibody assays as tools for monitoring SARS-CoV-2 immune responses. Future work should focus on investigating salivary antibody responses following infection and vaccination to understand patterns of SARS-CoV-2 transmission and inform ongoing vaccination strategies.

4.
BMJ Open ; 12(4): e062050, 2022 Apr 06.
Article in English | MEDLINE | ID: covidwho-1784843

ABSTRACT

INTRODUCTION: Persistent infection with HPV can result in cancers affecting men and, especially, women. Lower uptake exists by area and different population groups. Increasing parental confidence about, and adolescent access to, the universal HPV vaccination programme may help reduce inequalities in uptake. However, the evidence-base for interventions to address uptake for schools-based HPV vaccination programmes is currently lacking. This study protocol outlines how a multicomponent intervention to address this evidence gap will be codesigned with parents. METHODS AND ANALYSIS: The proposed research will be undertaken in localities covered by two immunisation teams in London and the south-west of England. The 'person-based approach' to intervention development will be followed. In the first phase, an exploratory qualitative study will be undertaken with key stakeholders (n=8) and parents (n=40) who did not provide consent for their adolescent child to be vaccinated. During the interviews, parents' views on ways to improve parental confidence about, and adolescents' access to, HPV vaccination will be sought. The findings will be used to inform the co-design of a preliminary plan for a targeted, multicomponent intervention. In the second phase, at least two parent working groups (n=8) will be convened and will work with creative designers to co-design communication materials aimed at increasing parents' confidence in vaccination. At least two workshops with each parent group will be organised to obtain feedback on the intervention plan and communication materials to ensure they are fit for purpose. These findings will inform a protocol for a future study to test the effectiveness of the intervention at increasing HPV vaccination uptake. ETHICS AND DISSEMINATION: The National Health Services Research Ethics Service and London School of Hygiene & Tropical Medicine Observational / Interventions Research Ethics Committee provided approvals for the study (reference 22/SW/0003 & 26902, respectively). We will work with parent advisory groups to inform our dissemination strategy and co-present our findings (eg, at community events or through social media). We will disseminate our findings with academics and healthcare professionals through webinars and academic conferences, as well as peer-reviewed publications.


Subject(s)
Papillomavirus Infections , Papillomavirus Vaccines , Adolescent , Child , England , Female , Humans , Male , Papillomavirus Infections/prevention & control , Parents , Vaccination
5.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-331007

ABSTRACT

Neutrophils are vital in defence against pathogens but excessive neutrophil activity can lead to tissue damage and promote acute respiratory distress syndrome (ARDS). COVID-19 is associated with systemic expansion of immature neutrophils but the functional consequences of this shift to immaturity are not understood. We used flow cytometry to investigate activity and phenotypic diversity of circulating neutrophils in COVID-19. First, we demonstrate hyperactivation of immature CD10- subpopulations in severe disease, with elevated degranulation of secondary granule markers. Partially activated immature neutrophils are detectable three months post symptom onset, indication long term myeloid dysregulation in convalescent COVID-19 patients. Second, we demonstrate that neutrophils from moderately ill patients downregulate the chemokine receptor CXCR2, while neutrophils from severely ill individuals failed to do so, suggesting altered ability for organ trafficking. CD10- and CXCR2hi neutrophil subpopulations were enriched in severe disease and may represent biomarkers for early identification of individuals at high risk of progressing to severe COVID-19.

6.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-315676

ABSTRACT

Background: Use of heterologous prime-boost COVID-19 vaccine schedules could facilitate mass COVID-19 immunisation, however we have previously reported that heterologous schedules incorporating an adenoviral-vectored vaccine (ChAd, Vaxzevria, Astrazeneca) and an mRNA vaccine (BNT, Comirnaty, Pfizer) at a 4-week interval are more reactogenic than homologous schedules. Here we report the immunogenicity of these schedules. Methods: Com-COV (ISRCTN: 69254139, EudraCT: 2020-005085-33) is a participant-blind, non-inferiority trial evaluating vaccine reactogenicity and immunogenicity. Adults ≥ 50 years, including those with well-controlled comorbidities, were randomised across eight groups to receive ChAd/ChAd, ChAd/BNT, BNT/BNT or BNT/ChAd, administered at 28- or 84-day intervals.The primary endpoint is geometric mean ratio (GMR) of serum SARS-CoV-2 anti-spike IgG levels (ELISA) at one-month post boost between heterologous and homologous schedules given the same prime vaccine. We tested non-inferiority of GMR using a margin of 0.63. The primary analysis was on a per-protocol population, who were seronegative at baseline. Safety analyses were performed amongst participants receiving at least one dose of study vaccines.Findings: In February 2021, 830 participants were enrolled and randomised, including 463 with a 28-day prime-boost interval whose results are reported in this paper. Participant mean age was 57.8 years, 45.8% were female, and 25.3% from ethnic minorities.The geometric mean concentration (GMC) of day 28 post-boost SARS-CoV-2 anti-spike IgG in ChAd/BNT recipients (12,906 ELU/ml) was non-inferior to that in ChAd/ChAd recipients (1,392 ELU/ml) with a geometric mean ratio (GMR) of 9.2 (one-sided 97.5% CI: 7.5, ∞). In participants primed with BNT, we failed to show non-inferiority of the heterologous schedule (BNT/ChAd, GMC 7,133 ELU/ml) against the homologous schedule (BNT/BNT, GMC 14,080 ELU/ml) with a GMR of 0.51 (one-sided 97.5% CI: 0.43, ∞). Geometric mean of T cell response at 28 days post boost in the ChAd/BNT group was 185 SFC/106 PBMCs (spot forming cells/106 peripheral blood mononuclear cells) compared to 50, 80 and 99 SFC/106 PBMCs for ChAd/ChAd, BNT/BNT, and BNT/ChAd, respectively. There were four serious adverse events across all groups, none of which were considered related to immunisation.Interpretation: Despite the BNT/ChAd regimen not meeting non-inferiority criteria, the GMCs of both heterologous schedules were higher than that of a licensed vaccine schedule (ChAd/ChAd) with proven efficacy against COVID-19 disease and hospitalisation. These data support flexibility in the use of heterologous prime-boost vaccination using ChAd and BNT COVID-19 vaccines.Trial Registration: The trial is registered at www.isrctn.com as ISRCTN: 69254139.Funding: Funded by the UK Vaccine Task Force (VTF) and National Institute for Health Research (NIHR)Declaration of Interest: MDS acts on behalf of the University of Oxford as an Investigator on studies funded or sponsored by vaccine manufacturers including AstraZeneca, GlaxoSmithKline, Pfizer, Novavax, Janssen, Medimmune, and MCM vaccines. He receives no personal financial payment for this work. JSN-V-T is seconded to the Department of Health and Social Care, England. AMC and DMF are investigators on studies funded by Pfizer and Unilever. They receive no personal financial payment for this work. AF is a member of the Joint Committee on Vaccination and Immunisation and Chair of the WHO European Technical Advisory Group of Experts (ETAGE) on Immunisation. He is an investigator and/or provides consultative advice on clinical trials and studies of COVID-19 vaccines produced by AstraZeneca, Janssen, Valneva, Pfizer and Sanofi and of other vaccines from these and other manufacturers including GSK, VPI, Takeda and Bionet Asia. He receives no personal remuneration or benefits for any of this work. SNF acts on behalf of University Hospital Southampton NHS Foundation Trust as an Inves igator and/or providing consultative advice on clinical trials and studies of COVID-19 and other vaccines funded or sponsored by vaccine manufacturers including Janssen, Pfizer, AstraZeneca, GlaxoSmithKline, Novavax, Seqirus, Sanofi, Medimmune, Merck and Valneva vaccines and antimicrobials. He receives no personal financial payment for this work. PTH acts on behalf of St. George’s University of London as an Investigator on clinical trials of COVID-19 vaccines funded or sponsored by vaccine manufacturers including Janssen, Pfizer, AstraZeneca, Novavax and Valneva. He receives no personal financial payment for this work. CAG acts on behalf of University Hospitals Birmingham NHS Foundation Trust as an Investigator on clinical trials and studies of COVID-19 and other vaccines funded or sponsored by vaccine manufacturers including Janssen, Pfizer, AstraZeneca, Novavax, CureVac, Moderna, and Valneva vaccines, and receives no personal financial payment for this work. VL acts on behalf of University College London Hospitals NHS Foundation Trust as an Investigator on clinical trials of COVID-19 vaccines funded or sponsored by vaccine manufacturers including Pfizer, AstraZeneca and Valneva. He receives no personal financial payment for this work. TL is named as an inventor on a patent application covering this SARS-CoV-2 vaccine and is an occasional consultant to Vaccitech unrelated to this work. Oxford University has entered into a partnership with AstraZeneca for further development of ChAdOx1 nCoV-19Ethical Approval: The trial was reviewed and approved by the South-Central Berkshire Research Ethics Committee (21/SC/0022), the University of Oxford, and the Medicines and Healthcare Products Regulatory Agency MHRA). An independent data safety monitoring board (DSMB) reviewed safety data, and local trial- site physicians provided oversight of all adverse events in real-time.

7.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-312866

ABSTRACT

Background: On 8th December 2020, deployment of the first vaccine against SARS-CoV-2 authorised for UK use, the mRNA-based vaccine BNT162b2, began, followed by the adenoviral vector vaccine ChAdOx1nCoV-19 on 4th January 2021. Initially care home-residents and staff, frontline healthcare workers and adults from age 80 were targeted. In phase 3 trials, BNT162b2 and ChAdOx1nCoV-19 demonstrated 95% and 70% efficacy, respectively, after two doses against symptomatic SARS-CoV-2 infection. However, few data exist regarding the effectiveness of these vaccines in elderly frail people. Evaluation following implementation to determine the effectiveness of one dose in reducing hospitalisations due to SARS-CoV-2 infection in elderly adults is urgent.Methods: A prospective single-centre test-negative design case-control study of adults aged ≥80 years hospitalised with COVID-19 disease or other acute respiratory disease. We conducted logistic regression controlling for time (week), gender, index of multiple deprivations (IMD), and care residency status (CRS), and sensitivity analyses matched for time and gender using a conditional logistic model adjusting for IMD and CRS.Findings: First dose vaccine effectiveness of BNT162b2 was 71.4% (95% confidence interval [CI] 46.5-90.6). ChAdOx1nCoV-19 first dose vaccine effectiveness was 80.4% (95% CI 36.4-94.5). When effectiveness analysis for BNT162b2 was restricted to the period covered by ChAdOx1nCoV-19, the estimate was 79.3% (95% CI 47.0-92.5).Interpretation: A single dose of either BNT162b2 or ChAdOx1nCoV-19 vaccine resulted in substantial reductions in the risk of COVID-19-related hospitalisation in elderly, frail patients with extensive co-morbid disease.Funding: The AvonCAP study is an investigator-led project funded under a collaborative agreement by Pfizer.Conflict of Interest: CH is Principal Investigator of the Avon CAP study which is an investigator-led University of Bristol study funded by Pfizer and has previously received support from the NIHR in an Academic Clinical Fellowship. JO is a Co-Investigator on the Avon CAP Study. AF is a member of the Joint Committee on Vaccination and Immunization (JCVI) and chair of the World Health Organization European Technical Advisory Group of Experts on Immunization (ETAGE) committee. In addition to receiving funding from Pfizer as Chief Investigator of this study, he leads another project investigating transmission of respiratory bacteria in families jointly funded by Pfizer and the Gates Foundation. The other authors have no relevant conflicts of interest to declare.Ethical Approval: The study was approved by the Health Research Authority Research Ethics Committee (East of England, Essex), REC 20/EE/0157, including data collection under Section 251 of the 2006 NHS Act authorised by the Confidentiality Advisory Group.

8.
Lancet Infect Dis ; 21(11): 1539-1548, 2021 11.
Article in English | MEDLINE | ID: covidwho-1633405

ABSTRACT

BACKGROUND: On Dec 8, 2020, deployment of the first SARS-CoV-2 vaccination authorised for UK use (BNT162b2 mRNA vaccine) began, followed by an adenoviral vector vaccine ChAdOx1 nCoV-19 on Jan 4, 2021. Care home residents and staff, frontline health-care workers, and adults aged 80 years and older were vaccinated first. However, few data exist regarding the effectiveness of these vaccines in older people with many comorbidities. In this post-implementation evaluation of two COVID-19 vaccines, we aimed to determine the effectiveness of one dose in reducing COVID-19-related admissions to hospital in people of advanced age. METHODS: This prospective test-negative case-control study included adults aged at least 80 years who were admitted to hospital in two NHS trusts in Bristol, UK with signs and symptoms of respiratory disease. Patients who developed symptoms before receiving their vaccine or those who received their vaccine after admission to hospital were excluded, as were those with symptoms that started more than 10 days before hospital admission. We did logistic regression analysis, controlling for time (week), sex, index of multiple deprivations, and care residency status, and sensitivity analyses matched for time and sex using a conditional logistic model adjusting for index of multiple deprivations and care residency status. This study is registered with ISRCTN, number 39557. FINDINGS: Between Dec 18, 2020, and Feb 26, 2021, 466 adults were eligible (144 test-positive and 322 test-negative). 18 (13%) of 135 people with SARS-CoV-2 infection and 90 (34%) of 269 controls received one dose of BNT162b2. The adjusted vaccine effectiveness was 71·4% (95% CI 46·5-90·6). Nine (25%) of 36 people with COVID-19 infection and 53 (59%) of 90 controls received one dose of ChAdOx1 nCoV-19. The adjusted vaccine effectiveness was 80·4% (95% CI 36·4-94·5). When BNT162b2 effectiveness analysis was restricted to the period covered by ChAdOx1 nCoV-19, the estimate was 79·3% (95% CI 47·0-92·5). INTERPRETATION: One dose of either BNT162b2 or ChAdOx1 nCoV-19 resulted in substantial risk reductions of COVID-19-related hospitalisation in people aged at least 80 years. FUNDING: Pfizer.


Subject(s)
COVID-19 Vaccines/immunology , COVID-19/prevention & control , Hospitalization/statistics & numerical data , Immunogenicity, Vaccine , Age Factors , Aged, 80 and over , COVID-19/diagnosis , COVID-19/epidemiology , COVID-19/virology , COVID-19 Nucleic Acid Testing/statistics & numerical data , COVID-19 Vaccines/administration & dosage , Case-Control Studies , England/epidemiology , Female , Humans , Immunization Schedule , Incidence , Male , Mass Vaccination/methods , Mass Vaccination/statistics & numerical data , SARS-CoV-2/genetics , SARS-CoV-2/immunology , SARS-CoV-2/isolation & purification , Treatment Outcome
9.
Lancet ; 399(10319): 36-49, 2022 01 01.
Article in English | MEDLINE | ID: covidwho-1557000

ABSTRACT

BACKGROUND: Given the importance of flexible use of different COVID-19 vaccines within the same schedule to facilitate rapid deployment, we studied mixed priming schedules incorporating an adenoviral-vectored vaccine (ChAdOx1 nCoV-19 [ChAd], AstraZeneca), two mRNA vaccines (BNT162b2 [BNT], Pfizer-BioNTech, and mRNA-1273 [m1273], Moderna) and a nanoparticle vaccine containing SARS-CoV-2 spike glycoprotein and Matrix-M adjuvant (NVX-CoV2373 [NVX], Novavax). METHODS: Com-COV2 is a single-blind, randomised, non-inferiority trial in which adults aged 50 years and older, previously immunised with a single dose of ChAd or BNT in the community, were randomly assigned (in random blocks of three and six) within these cohorts in a 1:1:1 ratio to receive a second dose intramuscularly (8-12 weeks after the first dose) with the homologous vaccine, m1273, or NVX. The primary endpoint was the geometric mean ratio (GMR) of serum SARS-CoV-2 anti-spike IgG concentrations measured by ELISA in heterologous versus homologous schedules at 28 days after the second dose, with a non-inferiority criterion of the GMR above 0·63 for the one-sided 98·75% CI. The primary analysis was on the per-protocol population, who were seronegative at baseline. Safety analyses were done for all participants who received a dose of study vaccine. The trial is registered with ISRCTN, number 27841311. FINDINGS: Between April 19 and May 14, 2021, 1072 participants were enrolled at a median of 9·4 weeks after receipt of a single dose of ChAd (n=540, 47% female) or BNT (n=532, 40% female). In ChAd-primed participants, geometric mean concentration (GMC) 28 days after a boost of SARS-CoV-2 anti-spike IgG in recipients of ChAd/m1273 (20 114 ELISA laboratory units [ELU]/mL [95% CI 18 160 to 22 279]) and ChAd/NVX (5597 ELU/mL [4756 to 6586]) was non-inferior to that of ChAd/ChAd recipients (1971 ELU/mL [1718 to 2262]) with a GMR of 10·2 (one-sided 98·75% CI 8·4 to ∞) for ChAd/m1273 and 2·8 (2·2 to ∞) for ChAd/NVX, compared with ChAd/ChAd. In BNT-primed participants, non-inferiority was shown for BNT/m1273 (GMC 22 978 ELU/mL [95% CI 20 597 to 25 636]) but not for BNT/NVX (8874 ELU/mL [7391 to 10 654]), compared with BNT/BNT (16 929 ELU/mL [15 025 to 19 075]) with a GMR of 1·3 (one-sided 98·75% CI 1·1 to ∞) for BNT/m1273 and 0·5 (0·4 to ∞) for BNT/NVX, compared with BNT/BNT; however, NVX still induced an 18-fold rise in GMC 28 days after vaccination. There were 15 serious adverse events, none considered related to immunisation. INTERPRETATION: Heterologous second dosing with m1273, but not NVX, increased transient systemic reactogenicity compared with homologous schedules. Multiple vaccines are appropriate to complete primary immunisation following priming with BNT or ChAd, facilitating rapid vaccine deployment globally and supporting recognition of such schedules for vaccine certification. FUNDING: UK Vaccine Task Force, Coalition for Epidemic Preparedness Innovations (CEPI), and National Institute for Health Research. NVX vaccine was supplied for use in the trial by Novavax.


Subject(s)
/administration & dosage , COVID-19 Vaccines/administration & dosage , COVID-19 Vaccines/adverse effects , Immunization, Secondary/adverse effects , Immunization, Secondary/methods , Immunogenicity, Vaccine , /administration & dosage , /administration & dosage , Aged , /immunology , COVID-19/prevention & control , COVID-19 Vaccines/immunology , /immunology , Female , Humans , Male , Middle Aged , Single-Blind Method , United Kingdom , Vaccination/adverse effects , Vaccination/methods , /immunology
10.
Lancet ; 398(10318): 2277-2287, 2021 12 18.
Article in English | MEDLINE | ID: covidwho-1510437

ABSTRACT

BACKGROUND: Concomitant administration of COVID-19 and influenza vaccines could reduce burden on health-care systems. We aimed to assess the safety of concomitant administration of ChAdOx1 or BNT162b2 plus an age-appropriate influenza vaccine. METHODS: In this multicentre, randomised, controlled, phase 4 trial, adults in receipt of a single dose of ChAdOx1 or BNT162b2 were enrolled at 12 UK sites and randomly assigned (1:1) to receive concomitant administration of either an age-appropriate influenza vaccine or placebo alongside their second dose of COVID-19 vaccine. 3 weeks later the group who received placebo received the influenza vaccine, and vice versa. Participants were followed up for 6 weeks. The influenza vaccines were three seasonal, inactivated vaccines (trivalent, MF59C adjuvanted or a cellular or recombinant quadrivalent vaccine). Participants and investigators were masked to the allocation. The primary endpoint was one or more participant-reported solicited systemic reactions in the 7 days after first trial vaccination(s), with a difference of less than 25% considered non-inferior. Analyses were done on an intention-to-treat basis. Local and unsolicited systemic reactions and humoral responses were also assessed. The trial is registered with ISRCTN, ISRCTN14391248. FINDINGS: Between April 1 and June 26, 2021, 679 participants were recruited to one of six cohorts, as follows: 129 ChAdOx1 plus cellular quadrivalent influenza vaccine, 139 BNT162b2 plus cellular quadrivalent influenza vaccine, 146 ChAdOx1 plus MF59C adjuvanted, trivalent influenza vaccine, 79 BNT162b2 plus MF59C adjuvanted, trivalent influenza vaccine, 128 ChAdOx1 plus recombinant quadrivalent influenza vaccine, and 58 BNT162b2 plus recombinant quadrivalent influenza vaccine. 340 participants were assigned to concomitant administration of influenza and a second dose of COVID-19 vaccine at day 0 followed by placebo at day 21, and 339 participants were randomly assigned to concomitant administration of placebo and a second dose of COVID-19 vaccine at day 0 followed by influenza vaccine at day 21. Non-inferiority was indicated in four cohorts, as follows: ChAdOx1 plus cellular quadrivalent influenza vaccine (risk difference for influenza vaccine minus placebos -1·29%, 95% CI -14·7 to 12·1), BNT162b2 plus cellular quadrivalent influenza vaccine (6·17%, -6·27 to 18·6), BNT162b2 plus MF59C adjuvanted, trivalent influenza vaccine (-12·9%, -34·2 to 8·37), and ChAdOx1 plus recombinant quadrivalent influenza vaccine (2·53%, -13·3 to 18·3). In the other two cohorts, the upper limit of the 95% CI exceeded the 0·25 non-inferiority margin (ChAdOx1 plus MF59C adjuvanted, trivalent influenza vaccine 10·3%, -5·44 to 26·0; BNT162b2 plus recombinant quadrivalent influenza vaccine 6·75%, -11·8 to 25·3). Most systemic reactions to vaccination were mild or moderate. Rates of local and unsolicited systemic reactions were similar between the randomly assigned groups. One serious adverse event, hospitalisation with severe headache, was considered related to the trial intervention. Immune responses were not adversely affected. INTERPRETATION: Concomitant vaccination with ChAdOx1 or BNT162b2 plus an age-appropriate influenza vaccine raises no safety concerns and preserves antibody responses to both vaccines. Concomitant vaccination with both COVID-19 and influenza vaccines over the next immunisation season should reduce the burden on health-care services for vaccine delivery, allowing for timely vaccine administration and protection from COVID-19 and influenza for those in need. FUNDING: National Institute for Health Research Policy Research Programme.


Subject(s)
/administration & dosage , COVID-19/prevention & control , Influenza Vaccines/administration & dosage , Influenza, Human/prevention & control , Adult , Aged , COVID-19/immunology , Female , Humans , Influenza Vaccines/immunology , Influenza, Human/immunology , Male , Middle Aged , SARS-CoV-2 , United Kingdom , Vaccines, Inactivated
11.
Arch Dis Child ; 107(3): e1, 2022 03.
Article in English | MEDLINE | ID: covidwho-1501687

ABSTRACT

Whether all children under 12 years of age should be vaccinated against COVID-19 remains an ongoing debate. The relatively low risk posed by acute COVID-19 in children, and uncertainty about the relative harms from vaccination and disease mean that the balance of risk and benefit of vaccination in this age group is more complex. One of the key arguments for vaccinating healthy children is to protect them from long-term consequences. Other considerations include population-level factors, such as reducing community transmission, vaccine supply, cost, and the avoidance of quarantine, school closures and other lockdown measures. The emergence of new variants of concern necessitates continual re-evaluation of the risks and benefits. In this review, we do not argue for or against vaccinating children against COVID-19 but rather outline the points to consider and highlight the complexity of policy decisions on COVID-19 vaccination in this age group.


Subject(s)
COVID-19 Vaccines , COVID-19/prevention & control , Mass Vaccination , Age Factors , COVID-19/complications , COVID-19/transmission , COVID-19 Vaccines/adverse effects , COVID-19 Vaccines/economics , COVID-19 Vaccines/supply & distribution , Child , Drug Costs , Humans , Pandemics/prevention & control , Risk Assessment , SARS-CoV-2
13.
Lancet ; 398(10303): 856-869, 2021 09 04.
Article in English | MEDLINE | ID: covidwho-1397746

ABSTRACT

BACKGROUND: Use of heterologous prime-boost COVID-19 vaccine schedules could facilitate mass COVID-19 immunisation. However, we have previously reported that heterologous schedules incorporating an adenoviral vectored vaccine (ChAdOx1 nCoV-19, AstraZeneca; hereafter referred to as ChAd) and an mRNA vaccine (BNT162b2, Pfizer-BioNTech; hereafter referred to as BNT) at a 4-week interval are more reactogenic than homologous schedules. Here, we report the safety and immunogenicity of heterologous schedules with the ChAd and BNT vaccines. METHODS: Com-COV is a participant-blinded, randomised, non-inferiority trial evaluating vaccine safety, reactogenicity, and immunogenicity. Adults aged 50 years and older with no or well controlled comorbidities and no previous SARS-CoV-2 infection by laboratory confirmation were eligible and were recruited at eight sites across the UK. The majority of eligible participants were enrolled into the general cohort (28-day or 84-day prime-boost intervals), who were randomly assigned (1:1:1:1:1:1:1:1) to receive ChAd/ChAd, ChAd/BNT, BNT/BNT, or BNT/ChAd, administered at either 28-day or 84-day prime-boost intervals. A small subset of eligible participants (n=100) were enrolled into an immunology cohort, who had additional blood tests to evaluate immune responses; these participants were randomly assigned (1:1:1:1) to the four schedules (28-day interval only). Participants were masked to the vaccine received but not to the prime-boost interval. The primary endpoint was the geometric mean ratio (GMR) of serum SARS-CoV-2 anti-spike IgG concentration (measured by ELISA) at 28 days after boost, when comparing ChAd/BNT with ChAd/ChAd, and BNT/ChAd with BNT/BNT. The heterologous schedules were considered non-inferior to the approved homologous schedules if the lower limit of the one-sided 97·5% CI of the GMR of these comparisons was greater than 0·63. The primary analysis was done in the per-protocol population, who were seronegative at baseline. Safety analyses were done among participants receiving at least one dose of a study vaccine. The trial is registered with ISRCTN, 69254139. FINDINGS: Between Feb 11 and Feb 26, 2021, 830 participants were enrolled and randomised, including 463 participants with a 28-day prime-boost interval, for whom results are reported here. The mean age of participants was 57·8 years (SD 4·7), with 212 (46%) female participants and 117 (25%) from ethnic minorities. At day 28 post boost, the geometric mean concentration of SARS-CoV-2 anti-spike IgG in ChAd/BNT recipients (12 906 ELU/mL) was non-inferior to that in ChAd/ChAd recipients (1392 ELU/mL), with a GMR of 9·2 (one-sided 97·5% CI 7·5 to ∞). In participants primed with BNT, we did not show non-inferiority of the heterologous schedule (BNT/ChAd, 7133 ELU/mL) against the homologous schedule (BNT/BNT, 14 080 ELU/mL), with a GMR of 0·51 (one-sided 97·5% CI 0·43 to ∞). Four serious adverse events occurred across all groups, none of which were considered to be related to immunisation. INTERPRETATION: Despite the BNT/ChAd regimen not meeting non-inferiority criteria, the SARS-CoV-2 anti-spike IgG concentrations of both heterologous schedules were higher than that of a licensed vaccine schedule (ChAd/ChAd) with proven efficacy against COVID-19 disease and hospitalisation. Along with the higher immunogenicity of ChAd/BNT compared with ChAD/ChAd, these data support flexibility in the use of heterologous prime-boost vaccination using ChAd and BNT COVID-19 vaccines. FUNDING: UK Vaccine Task Force and National Institute for Health Research.


Subject(s)
COVID-19 Vaccines/adverse effects , COVID-19 Vaccines/immunology , COVID-19/prevention & control , Immunogenicity, Vaccine , Aged , Antibodies, Viral/blood , COVID-19 Vaccines/administration & dosage , Equivalence Trials as Topic , Female , Humans , Immunization Schedule , Immunoglobulin G/blood , Intention to Treat Analysis , Male , Middle Aged , Single-Blind Method , Spike Glycoprotein, Coronavirus/immunology
15.
Nat Commun ; 12(1): 5017, 2021 08 17.
Article in English | MEDLINE | ID: covidwho-1361635

ABSTRACT

Controlling COVID-19 transmission in universities poses challenges due to the complex social networks and potential for asymptomatic spread. We developed a stochastic transmission model based on realistic mixing patterns and evaluated alternative mitigation strategies. We predict, for plausible model parameters, that if asymptomatic cases are half as infectious as symptomatic cases, then 15% (98% Prediction Interval: 6-35%) of students could be infected during the first term without additional control measures. First year students are the main drivers of transmission with the highest infection rates, largely due to communal residences. In isolation, reducing face-to-face teaching is the most effective intervention considered, however layering multiple interventions could reduce infection rates by 75%. Fortnightly or more frequent mass testing is required to impact transmission and was not the most effective option considered. Our findings suggest that additional outbreak control measures should be considered for university settings.


Subject(s)
COVID-19/epidemiology , COVID-19/transmission , Universities , Disease Outbreaks/prevention & control , Humans , Models, Biological , SARS-CoV-2/isolation & purification , Students , Surveys and Questionnaires , United Kingdom/epidemiology
16.
Epidemiology and Infection ; 149, 2021.
Article in English | ProQuest Central | ID: covidwho-1351911

ABSTRACT

UK universities re-opened in September 2020, amidst the coronavirus epidemic. During the first term, various national social distancing measures were introduced, including banning groups of >6 people and the second lockdown in November;however, outbreaks among university students occurred. We aimed to measure the University of Bristol staff and student contact patterns via an online, longitudinal survey capturing self-reported contacts on the previous day. We investigated the change in contacts associated with COVID-19 guidance periods: post-first lockdown (23/06/2020–03/07/2020), relaxed guidance period (04/07/2020–13/09/2020), ‘rule-of-six’ period (14/09/2020–04/11/2020) and the second lockdown (05/11/2020–25/11/2020). In total, 722 staff (4199 responses) and 738 students (1906 responses) were included in the study. For staff, daily contacts were higher in the relaxed guidance and ‘rule-of-six’ periods than the post-first lockdown and second lockdown. Mean student contacts dropped between the ‘rule-of-six’ and second lockdown periods. For both staff and students, the proportion meeting with groups larger than six dropped between the ‘rule-of-six’ period and the second lockdown period, although was higher for students than for staff. Our results suggest university staff and students responded to national guidance by altering their social contacts. Most contacts during the second lockdown were household contacts. The response in staff and students was similar, suggesting that students can adhere to social distancing guidance while at university. The number of contacts recorded for both staff and students were much lower than those recorded by previous surveys in the UK conducted before the COVID-19 pandemic.

18.
Cell Rep Med ; 2(7): 100327, 2021 07 20.
Article in English | MEDLINE | ID: covidwho-1275765

ABSTRACT

Severe COVID-19 appears rare in children. This is unexpected, especially in young infants, who are vulnerable to severe disease caused by other respiratory viruses. We evaluate convalescent immune responses in 4 infants under 3 months old with confirmed COVID-19 who presented with mild febrile illness, alongside their parents, and adult controls recovered from confirmed COVID-19. Although not statistically significant, compared to seropositive adults, infants have high serum levels of IgG and IgA to SARS-CoV-2 spike protein, with a corresponding functional ability to block SARS-CoV-2 cellular entry. Infants also exhibit robust saliva anti-spike IgG and IgA responses. Spike-specific IFN-γ production by infant peripheral blood mononuclear cells appears restrained, but the frequency of spike-specific IFN-γ- and/or TNF-α-producing T cells is comparable between infants and adults. On principal-component analysis, infant immune responses appear distinct from their parents. Robust functional antibody responses alongside restrained IFN-γ production may help protect infants from severe COVID-19.


Subject(s)
Antibody Formation , COVID-19/immunology , Interferon-gamma/metabolism , Spike Glycoprotein, Coronavirus/immunology , Adult , Female , Humans , Immunoglobulin A , Immunoglobulin G , Infant , Infant, Newborn , Interferon-gamma/immunology , Leukocytes, Mononuclear/metabolism , Male , Young Adult
19.
Sci Rep ; 11(1): 11728, 2021 06 03.
Article in English | MEDLINE | ID: covidwho-1258594

ABSTRACT

University students have unique living, learning and social arrangements which may have implications for infectious disease transmission. To address this data gap, we created CONQUEST (COroNavirus QUESTionnaire), a longitudinal online survey of contacts, behaviour, and COVID-19 symptoms for University of Bristol (UoB) staff/students. Here, we analyse results from 740 students providing 1261 unique records from the start of the 2020/2021 academic year (14/09/2020-01/11/2020), where COVID-19 outbreaks led to the self-isolation of all students in some halls of residences. Although most students reported lower daily contacts than in pre-COVID-19 studies, there was heterogeneity, with some reporting many (median = 2, mean = 6.1, standard deviation = 15.0; 8% had ≥ 20 contacts). Around 40% of students' contacts were with individuals external to the university, indicating potential for transmission to non-students/staff. Only 61% of those reporting cardinal symptoms in the past week self-isolated, although 99% with a positive COVID-19 test during the 2 weeks before survey completion had self-isolated within the last week. Some students who self-isolated had many contacts (mean = 4.3, standard deviation = 10.6). Our results provide context to the COVID-19 outbreaks seen in universities and are available for modelling future outbreaks and informing policy.


Subject(s)
COVID-19/etiology , COVID-19/psychology , Quarantine/statistics & numerical data , Students/psychology , Universities , Adult , Aged , COVID-19/epidemiology , Female , Humans , Longitudinal Studies , Male , Middle Aged , Quarantine/psychology , Regression Analysis , Social Isolation , Students/statistics & numerical data , Surveys and Questionnaires , United Kingdom , Young Adult
20.
Lancet ; 397(10277): 881-891, 2021 03 06.
Article in English | MEDLINE | ID: covidwho-1174543

ABSTRACT

BACKGROUND: 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.


Subject(s)
COVID-19 Vaccines/administration & dosage , COVID-19 Vaccines/immunology , COVID-19/prevention & control , Immunization Schedule , Immunization, Secondary , Adolescent , Adult , Aged , Antibody Formation , Asymptomatic Infections , COVID-19 Vaccines/adverse effects , Humans , Middle Aged , Randomized Controlled Trials as Topic , SARS-CoV-2/immunology , Young Adult
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