The message emerging from expert dialogue on the trajectory of COVID is increasingly clear: this show won’t be over until the whole world is vaccinated. The appearance of Omicron on the scene, with son-of-Omicron (the BA.2 sub-variant) hot on its heels, has been a stark reminder that making it through one wave doesn’t mean we’ve weathered the storm – as long as there are under-vaccinated populations, this virus will continue to develop new variants that will sweep across the globe, making vaccine equity crucial to COVID defense.
Just how much should we prioritise vaccine sharing over increasing immunity within our own borders? A new modelling study published in Nature Human Behaviour has put firm figures to this tricky question, finding that if high-income countries were to donate up to 46% of their total vaccine supply to low- and middle-income countries, the benefits could include substantial decreases in global mortality and protection against further pandemic waves.
Using a mathematical model, the researchers projected the consequences of vaccine inequity over five years, against the backdrop of evolving strains of SARS-CoV-2 and global mobility.
The results showed that if we want to get on top of COVID, we’re going to have look beyond short-term immunity gains within our own borders and start playing a globally focused long-game.
The model indicated that increasing national vaccination rates through booster programs, such as the controversial four-dose regime being rolled out across Israel, does lead to faster declines in mortality in high-income countries in the first year. But these gains are swallowed up by an increasing vulnerability to infection in subsequent years as the global threat of newly emerging strains grows.
Conversely, modelling equitable vaccine allocation strategies showed a substantial curbing of the spread of new strains, providing greater benefits to both high-income and low- and middle-income countries.
Regardless of where individual countries stand on the ethics of tending to your own flock ahead of assisting disadvantaged global populations, this model makes it clear that allocating nearly half of high-income countries’ vaccine supplies is, over the longer-term, in their own interest.
Addressing vaccine equity is a practical but highly effective variant-suppression measure that could be achieved by immediate and more-generous vaccine donations to low- and middle-income countries, but convincing governments to reframe their national COVID strategies in this global light remains a challenge.
As of 31 December 2021, more than nine billion COVID-19 vaccination doses had been administered worldwide – but the distribution of these doses remains highly imbalanced. Over 70% of people in high-income countries are now fully vaccinated against COVID-19; in low-income countries, that number is 4%.
Organisations such as COVAX, which is co-led by Gavi, the WHO, and CEPI, are attempting to tackle the vaccine inequity problem, and announced in January that they had delivered their billionth vaccine dose – an admirable achievement, but well short of their 2 billion dose goal. The organisation cited hoarding and stockpiling by wealthy countries as a key roadblock to their progress. Many high-income countries have access to enough vaccines to vaccinate their populations several times over, leaving some low- and middle-income countries struggling to obtain sufficient supplies to vaccinate their populations even once.
But, as the current study makes clear, pandemics pay no heed to borders. Until there is international commitment to global vaccine equity, the waves will continue to crash in.
Jamie Priest is a science journalist at Cosmos. She has a Bachelor of Science in Marine Biology from the University of Adelaide.
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