Using absolute risk reduction to guide the equitable distribution of COVID-19 vaccines

Fassler, Ella; Larkin, Andrew; Nayar, Kesavan Rajasekharan; Waitzkin, Howard

doi:10.1136/bmjebm-2021-111789

Cited by 2 publications

(2 citation statements)

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“…A strategy emphasising vaccines’ differential impacts on reducing absolute risk in targeted geographical areas could alleviate some economic and practical burdens of trying to provide vaccines for everyone, especially in poorer regions. 71 If resources to support full EBM analyses are not available, using observed prevalence to guide geographical priorities in vaccine distribution could become a satisfactory alternative. Realistically, some decision-makers in power may not support such policies that favour disadvantaged groups.…”

Section: Discussionmentioning

confidence: 99%

“…Vaccine distribution should target subpopulations with higher baseline risks of disease, rather than focusing only on the goal of vaccinating entire populations. A strategy emphasising vaccines’ differential impacts on reducing absolute risk in targeted geographical areas could alleviate some economic and practical burdens of trying to provide vaccines for everyone, especially in poorer regions 71. If resources to support full EBM analyses are not available, using observed prevalence to guide geographical priorities in vaccine distribution could become a satisfactory alternative.…”

Section: Discussionmentioning

confidence: 99%

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How missing evidence-based medicine indicators can inform COVID-19 vaccine distribution policies: a scoping review and calculation of indicators from data in randomised controlled trials

et al. 2022

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ObjectiveReports of efficacy, effectiveness and harms of COVID-19 vaccines have not used key indicators from evidence-based medicine (EBM) that can inform policies about vaccine distribution. This study aims to clarify EBM indicators that consider baseline risks when assessing vaccines’ benefits versus harms: absolute risk reduction (ARR) and number needed to be vaccinated (NNV), versus absolute risk of the intervention (ARI) and number needed to harm (NNH).MethodsWe used a multimethod approach, including a scoping review of the literature; calculation of risk reductions and harms from data concerning five major vaccines; analysis of risk reductions in population subgroups with varying baseline risks; and comparisons with prior vaccines.FindingsThe scoping review showed few reports regarding ARR, NNV, ARI and NNH; comparisons of benefits versus harms using these EBM methods; or analyses of varying baseline risks. Calculated ARRs for symptomatic infection and hospitalisation were approximately 1% and 0.1%, respectively, as compared with relative risk reduction of 50%–95% and 58%–100%. NNV to prevent one symptomatic infection and one hospitalisation was in the range of 80–500 and 500–4000. Based on available data, ARI and NNH as measures of harm were difficult to calculate, and the balance between benefits and harms using EBM measures remained uncertain. The effectiveness of COVID-19 vaccines as measured by ARR and NNV was substantially higher in population subgroups with high versus low baseline risks.ConclusionsPriorities for vaccine distribution should target subpopulations with higher baseline risks. Similar analyses using ARR/NNV and ARI/NNH would strengthen evaluations of vaccines’ benefits versus harms. An EBM perspective on vaccine distribution that emphasises baseline risks becomes especially important as the world’s population continues to face major barriers to vaccine access—sometimes termed ‘vaccine apartheid’.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%