Models of COVID-19 vaccine prioritisation: a systematic literature search and narrative review

  1. Nuru Saadi
  2. Y-Ling Chi
  3. Srobana Ghosh
  4. Rosalind M. Eggo
  5. Ciara V. McCarthy
  6. Matthew Quaife
  7. Jeanette Dawa
  8. Mark Jit
  9. Anna Vassall

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Abstract

Background

How best to prioritise COVID-19 vaccination within and between countries has been a public health and an ethical challenge for decision-makers globally. We reviewed epidemiological and economic modelling evidence on population priority groups to minimise COVID-19 mortality, transmission, and morbidity outcomes.

Methods

We searched the National Institute of Health iSearch COVID-19 Portfolio (a database of peer-reviewed and pre-print articles), Econlit, the Centre for Economic Policy Research, and the National Bureau of Economic Research for mathematical modelling studies evaluating the impact of prioritising COVID-19 vaccination to population target groups. The first search was conducted on March 3, 2021, and an updated search on the LMIC literature was conducted from March 3, 2021, to September 24, 2021. We narratively synthesised the main study conclusions on prioritisation and the conditions under which the conclusions changed.

Results

The initial search identified 1820 studies and 36 studies met the inclusion criteria. The updated search on LMIC literature identified 7 more studies. 43 studies in total were narratively synthesised. 74% of studies described outcomes in high-income countries (single and multi-country). We found that for countries seeking to minimise deaths, prioritising vaccination of senior adults was the optimal strategy and for countries seeking to minimise cases the young were prioritised. There were several exceptions to the main conclusion, notably that reductions in deaths could be increased if groups at high risk of both transmission and death could be further identified. Findings were also sensitive to the level of vaccine coverage.

Conclusion

The evidence supports WHO SAGE recommendations on COVID-19 vaccine prioritisation. There is, however, an evidence gap on optimal prioritisation for low- and middle-income countries, studies that included an economic evaluation, and studies that explore prioritisation strategies if the aim is to reduce overall health burden including morbidity.

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  1. Version published to 10.1186/s12916-021-02190-3
  2. ScreenIT

    SciScore for 10.1101/2021.06.21.21259104: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Ethicsnot detected.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    iSearch COVID-19 Portfolio on the 3rd of March 2021 (a database which sources peer-reviewed articles from Pubmed and preprints from arXiv, bioRxiv, ChemRxiv, medRxiv, Preprints.org, Qeios, Research Square, and SSRN).
    Pubmed
    suggested: (PubMed, RRID:SCR_004846)
    arXiv
    suggested: (arXiv, RRID:SCR_006500)
    bioRxiv
    suggested: (bioRxiv, RRID:SCR_003933)
    Data were recorded in Microsoft Excel files summarising the policy objectives, outcomes, characteristics of the studies, the study conclusions and the conditions under which the conclusions changed i.e. sensitivity analyses (see supplementary materials to download the full extraction sheet).
    Microsoft Excel
    suggested: (Microsoft Excel, RRID:SCR_016137)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    [31] [32] [24] [23] Chen et al. suggest those population groups could be identified through contact tracing, although recognising the limitations of such an approach in resource constrained settings. [23] Santini recommends prioritising younger people with many connections to vulnerable people. [24] Buckner et al. find that prioritising essential workers (based on occupation) could lead to fewer deaths in the context of strong non-pharmaceutical interventions. [28] As no studies included the feasibility and costs of identifying and delivering vaccines to highly-connected groups, it is unclear whether prioritisation to groups that are not age or occupation-based is possible or cost-effective. Luangasanatip et al. examined how vaccines may be prioritised in a low-incidence setting (Thailand). [33] finding that prioritising younger age groups would lead to greater reductions in deaths. However, this was the only study set in a low incidence setting, so more research may be required to validate this finding across settings and modelling approaches. The small number of studies set in low- and middle-income countries, and the lack of evidence on the cost-effectiveness of reaching different population also limits our findings in resource constrained settings. Although we found that most of the studies modelling these settings were in line with the conclusions from studies set in HIC for minimising deaths and cases, context may impact results, especially when very limited supply is c...

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    Results from scite Reference Check: We found no unreliable references.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  3. Version published to 10.1101/2021.06.21.21259104 on medRxiv