Table 1.

Policy summary

Background	The SARS-CoV-2 pandemic has caused considerable morbidity and mortality worldwide. Although the protection offered by vaccines (and booster doses) offers a method of mitigating the worst effects, by the end of 2021 the distribution of vaccine was highly heterogeneous, with some countries achieving over 90% coverage in adults, whereas others reached less than 2%. In part, this is due to the availability of sufficient vaccine, although vaccine hesitancy also plays a role. We combined estimates of historic SARS-CoV-2 infections and vaccine uptake with an age-structured model for 152 countries to consider the implications of different vaccine sharing policies that go some way to addressing this imbalance.
Main findings and limitations	We calculated that increased vaccine sharing, without any changes to NPIs, would have substantially reduced COVID-19 infection mortality in lower-income countries, although some high-income countries would have had increased mortality unless additional measures were taken. Overall, we estimate that this vaccine sharing scenario would have prevented 1.3 million deaths worldwide (as a direct result of COVID-19) by the end of 2021, although this figure could be substantially increased if increased vaccine sharing from high-income countries had been compensated for with slower easing of NPIs. This global decrease in mortality is due to a combination of greater protection of the most vulnerable and the lower level of global infection, leading to fewer opportunities for new variants to arise. This study is limited to considering vaccine supply constraints, although additional pressures induced by uptake hesitancy and delivery limitations are becoming increasingly relevant.
Policy implications	Although the focus of this work is a retrospective study of the COVID-19 pandemic, there are naturally conclusions to be drawn about national and international policies going forward. Our simulations provide strong analytical evidence to support the message that distributing vaccines across the globe proportional to need, rather than to wealth, can have beneficial effects for all.