{"doi":"10.1056/nejmoa2102214","title":"Efficacy of the ChAdOx1 nCoV-19 Covid-19 Vaccine against the B.1.351 Variant","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: 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).","journal":"New England Journal of Medicine","year":2021,"id":145020,"datarank":13.34094621403594,"base_score":7.186901020411631,"endowment":7.186901020411631,"self_citation_contribution":1.078035153061745,"citation_network_contribution":12.262911060974195,"self_endowment_contribution":1.078035153061745,"citer_contribution":12.262911060974195,"corpus_percentile":null,"corpus_rank":null,"citation_count":1321,"citer_count":100,"citers_with_citation_signal":100,"citers_with_endowment":100,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9539,"is_data_producer":true,"deposit_databanks":{"ClinicalTrials.gov":["NCT04444674"],"PACTR":["PACTR202006922165132"]},"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":242152,"name":"Vicky L. Baillie","orcid":"0000-0003-1327-9090","position":1,"is_corresponding":false},{"id":501623,"name":"Clare Cutland","orcid":"0000-0001-8250-8307","position":2,"is_corresponding":false},{"id":614522,"name":"Merryn Voysey","orcid":"0000-0001-6324-6559","position":3,"is_corresponding":false},{"id":614523,"name":"Anthonet Koen","orcid":"0000-0001-6420-8511","position":4,"is_corresponding":false},{"id":473780,"name":"Lee Fairlie","orcid":"0000-0001-5327-1734","position":5,"is_corresponding":false},{"id":616503,"name":"Sherman D. Padayachee","orcid":null,"position":6,"is_corresponding":false},{"id":528806,"name":"Keertan Dheda","orcid":"0000-0001-7709-5341","position":7,"is_corresponding":false},{"id":307183,"name":"Shaun Barnabas","orcid":"0000-0002-4819-9501","position":8,"is_corresponding":false},{"id":614524,"name":"Qasim Bhorat","orcid":"0000-0002-4102-8750","position":9,"is_corresponding":false},{"id":614525,"name":"Carmen Briner","orcid":"0000-0002-7580-7605","position":10,"is_corresponding":false},{"id":616504,"name":"Gaurav Kwatra","orcid":null,"position":11,"is_corresponding":false},{"id":438005,"name":"Khatija Ahmed","orcid":"0000-0003-0309-1641","position":12,"is_corresponding":false},{"id":614526,"name":"Parvinder K. Aley","orcid":"0000-0002-0749-8329","position":13,"is_corresponding":false},{"id":616505,"name":"Sutika Bhikha","orcid":null,"position":14,"is_corresponding":false},{"id":138626,"name":"Jinal N. Bhiman","orcid":"0000-0001-6354-4003","position":15,"is_corresponding":false},{"id":614527,"name":"As’ad E. Bhorat","orcid":"0000-0002-8764-7020","position":16,"is_corresponding":false},{"id":616506,"name":"Jeanine du Plessis","orcid":null,"position":17,"is_corresponding":false},{"id":528805,"name":"Aliasgar Esmail","orcid":"0000-0002-1835-9252","position":18,"is_corresponding":false},{"id":616507,"name":"Marisa Groenewald","orcid":null,"position":19,"is_corresponding":false},{"id":318055,"name":"Elizea Horne","orcid":"0000-0002-9236-3110","position":20,"is_corresponding":false},{"id":614528,"name":"Shi-Hsia Hwa","orcid":"0000-0002-5648-9808","position":21,"is_corresponding":false},{"id":616508,"name":"Aylin Jose","orcid":null,"position":22,"is_corresponding":false},{"id":107160,"name":"Teresa Lambe","orcid":"0000-0001-7711-897X","position":23,"is_corresponding":false},{"id":242146,"name":"Matt Laubscher","orcid":"0009-0007-7835-0421","position":24,"is_corresponding":false},{"id":355218,"name":"Mookho Malahleha","orcid":"0000-0003-1879-8471","position":25,"is_corresponding":false},{"id":616509,"name":"Masebole Masenya","orcid":null,"position":26,"is_corresponding":false},{"id":616510,"name":"Mduduzi Masilela","orcid":null,"position":27,"is_corresponding":false},{"id":616511,"name":"Shakeel McKenzie","orcid":null,"position":28,"is_corresponding":false},{"id":616512,"name":"Kgaogelo Molapo","orcid":null,"position":29,"is_corresponding":false},{"id":501624,"name":"Andrew Moultrie","orcid":"0000-0002-8222-4168","position":30,"is_corresponding":false},{"id":614529,"name":"Suzette Oelofse","orcid":"0000-0001-7852-7804","position":31,"is_corresponding":false},{"id":346850,"name":"Faeezah Patel","orcid":"0000-0003-1503-2016","position":32,"is_corresponding":false},{"id":282132,"name":"Sureshnee Pillay","orcid":"0000-0001-9288-7996","position":33,"is_corresponding":false},{"id":614530,"name":"Sarah Rhead","orcid":"0000-0002-4755-281X","position":34,"is_corresponding":false},{"id":614531,"name":"Hylton Rodel","orcid":"0000-0001-6338-6375","position":35,"is_corresponding":false},{"id":616513,"name":"Lindie Rossouw","orcid":null,"position":36,"is_corresponding":false},{"id":616514,"name":"Carol Taoushanis","orcid":null,"position":37,"is_corresponding":false},{"id":282134,"name":"Houriiyah Tegally","orcid":"0000-0002-7102-8540","position":38,"is_corresponding":false},{"id":616515,"name":"Asha Thombrayil","orcid":null,"position":39,"is_corresponding":false},{"id":616516,"name":"Samuel van Eck","orcid":null,"position":40,"is_corresponding":false},{"id":429743,"name":"Constantinos Kurt Wibmer","orcid":"0000-0003-2329-2280","position":41,"is_corresponding":false},{"id":614532,"name":"Nicholas M. Durham","orcid":"0000-0003-1065-8474","position":42,"is_corresponding":false},{"id":614533,"name":"Elizabeth J. Kelly","orcid":"0000-0002-6988-8576","position":43,"is_corresponding":false},{"id":614534,"name":"Tonya Villafana","orcid":"0000-0001-7929-6374","position":44,"is_corresponding":false},{"id":107193,"name":"Sarah C. Gilbert","orcid":"0000-0002-6823-9750","position":45,"is_corresponding":false},{"id":78476,"name":"Andrew J. Pollard","orcid":"0000-0001-7361-719X","position":46,"is_corresponding":false},{"id":279259,"name":"Túlio de Oliveira","orcid":"0000-0002-3027-5254","position":47,"is_corresponding":false},{"id":138629,"name":"Penny L. Moore","orcid":"0000-0001-8719-4028","position":48,"is_corresponding":false},{"id":584140,"name":"Alex Sigal","orcid":"0000-0001-8571-2004","position":49,"is_corresponding":false},{"id":614535,"name":"Alane Izu","orcid":"0000-0002-5547-7223","position":50,"is_corresponding":false},{"id":227043,"name":"Shabir A. Madhi","orcid":"0000-0002-7629-0636","position":0,"is_corresponding":true}],"reference_count":25,"raw_metadata":null,"created_at":"2026-07-18T23:41:52.374756Z","pmid":"33725432","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}