Estimating the effectiveness of first dose of COVID-19 vaccine against mortality in England: a quasi-experimental study

Estimating real-world vaccine effectiveness is vital to assessing the coronavirus disease 2019 (COVID-19) vaccination program and informing the ongoing policy response. However, estimating vaccine effectiveness using observational data is inherently challenging because of the nonrandomized design an...

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Main Authors: Bermingham, C, Morgan, J, Ayoubkhani, D, Glickman, M, Islam, N, Sheikh, A, Sterne, J, Walker, AS, Nafilyan, V
Format: Journal article
Language:English
Published: Oxford University Press 2022
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author Bermingham, C
Morgan, J
Ayoubkhani, D
Glickman, M
Islam, N
Sheikh, A
Sterne, J
Walker, AS
Nafilyan, V
author_facet Bermingham, C
Morgan, J
Ayoubkhani, D
Glickman, M
Islam, N
Sheikh, A
Sterne, J
Walker, AS
Nafilyan, V
author_sort Bermingham, C
collection OXFORD
description Estimating real-world vaccine effectiveness is vital to assessing the coronavirus disease 2019 (COVID-19) vaccination program and informing the ongoing policy response. However, estimating vaccine effectiveness using observational data is inherently challenging because of the nonrandomized design and potential for unmeasured confounding. We used a regression discontinuity design to estimate vaccine effectiveness against COVID-19 mortality in England using the fact that people aged 80 years or older were prioritized for the vaccine rollout. The prioritization led to a large discrepancy in vaccination rates among people aged 80–84 years compared with those aged 75–79 at the beginning of the vaccination campaign. We found a corresponding difference in COVID-19 mortality but not in non-COVID-19 mortality, suggesting that our approach appropriately addressed the issue of unmeasured confounding factors. Our results suggest that the first vaccine dose reduced the risk of COVID-19 death by 52.6% (95% confidence limits: 15.7, 73.4) in those aged 80 years, supporting existing evidence that a first dose of a COVID-19 vaccine had a strong protective effect against COVID-19 mortality in older adults. The regression discontinuity model’s estimate of vaccine effectiveness is only slightly lower than those of previously published studies using different methods, suggesting that these estimates are unlikely to be substantially affected by unmeasured confounding factors.
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spelling oxford-uuid:0d9b9ca7-b3bb-4bc2-bcb7-118f47148a4a2023-09-05T16:41:57ZEstimating the effectiveness of first dose of COVID-19 vaccine against mortality in England: a quasi-experimental studyJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:0d9b9ca7-b3bb-4bc2-bcb7-118f47148a4aEnglishSymplectic ElementsOxford University Press2022Bermingham, CMorgan, JAyoubkhani, DGlickman, MIslam, NSheikh, ASterne, JWalker, ASNafilyan, VEstimating real-world vaccine effectiveness is vital to assessing the coronavirus disease 2019 (COVID-19) vaccination program and informing the ongoing policy response. However, estimating vaccine effectiveness using observational data is inherently challenging because of the nonrandomized design and potential for unmeasured confounding. We used a regression discontinuity design to estimate vaccine effectiveness against COVID-19 mortality in England using the fact that people aged 80 years or older were prioritized for the vaccine rollout. The prioritization led to a large discrepancy in vaccination rates among people aged 80–84 years compared with those aged 75–79 at the beginning of the vaccination campaign. We found a corresponding difference in COVID-19 mortality but not in non-COVID-19 mortality, suggesting that our approach appropriately addressed the issue of unmeasured confounding factors. Our results suggest that the first vaccine dose reduced the risk of COVID-19 death by 52.6% (95% confidence limits: 15.7, 73.4) in those aged 80 years, supporting existing evidence that a first dose of a COVID-19 vaccine had a strong protective effect against COVID-19 mortality in older adults. The regression discontinuity model’s estimate of vaccine effectiveness is only slightly lower than those of previously published studies using different methods, suggesting that these estimates are unlikely to be substantially affected by unmeasured confounding factors.
spellingShingle Bermingham, C
Morgan, J
Ayoubkhani, D
Glickman, M
Islam, N
Sheikh, A
Sterne, J
Walker, AS
Nafilyan, V
Estimating the effectiveness of first dose of COVID-19 vaccine against mortality in England: a quasi-experimental study
title Estimating the effectiveness of first dose of COVID-19 vaccine against mortality in England: a quasi-experimental study
title_full Estimating the effectiveness of first dose of COVID-19 vaccine against mortality in England: a quasi-experimental study
title_fullStr Estimating the effectiveness of first dose of COVID-19 vaccine against mortality in England: a quasi-experimental study
title_full_unstemmed Estimating the effectiveness of first dose of COVID-19 vaccine against mortality in England: a quasi-experimental study
title_short Estimating the effectiveness of first dose of COVID-19 vaccine against mortality in England: a quasi-experimental study
title_sort estimating the effectiveness of first dose of covid 19 vaccine against mortality in england a quasi experimental study
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