Even an imperfect, partially effective vaccine against COVID-19 could have a substantial public health benefit if rolled out in 2021, a report says.

Researchers from Imperial’s COVID-19 Response Team also found that the optimal approach to allocating vaccine doses within a country will require a detailed understanding of the local setting – including relevant risk groups and the stage and spread of the epidemic.

With limited supply, this might involve targeting elderly and other high-risk groups. With larger supply available to a country, a more efficient strategy would be to vaccinate the working-age population.

The researchers found that as supply increases, vaccines that reduce or block infection – and thus transmission – in addition to preventing disease have a substantial greater impact than those that prevent disease alone, due to the indirect protection provided to high-risk groups.

Even under optimistic scenarios for manufacture and delivery, the doses available in 2021 are likely to be limited. In this report, researchers explore the impact of vaccine allocation within countries and between countries to maximise health and avert deaths under constraints on dose supply.

Allocating the limited doses likely to be available in 2021 to countries according to their population size is almost as efficient as more nuanced strategies. Such a strategy also aligns with the ethical principles agreed in pandemic preparedness planning. Defining the “optimal” strategy ahead of time is challenging because it is sensitive to vaccine characteristics that will not be fully known at the time of roll-out.

Global public health value of the vaccine can be maximised by ensuring equitable access: acting collectively in this way during the early stages of vaccine deployment remains the ethical approach to take, even if this is not the most beneficial short-term strategy from a national perspective, according to this report.

Research and development of a SARS-CoV-2 vaccine has taken place at unprecedented speed such that it is likely that efficacy and safety data will be available for one or more of the leading vaccine candidates within one year of the pandemic being declared.


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