The findings, published in the journal The BMJ, suggest that the operational challenges of the global Covid-19 vaccination programme will be at least as difficult as the scientific challenges associated with their development.

 

In the first study, researchers from the Johns Hopkins University in the US analysed pre-orders for Covid-19 vaccines ahead of their regulatory approval that had been publicly announced by countries around the world.

 

By 15 November 2020, several countries had reserved a total of 7.48 billion doses, or 3.76 billion courses from 13 manufacturers, out of 48 Covid-19 vaccine candidates in clinical trials.

 

"Just over half (51 per cent) of these doses will go to high income countries, which represent 14 per cent of the world's population, the study authors wrote.

 

Low and middle income countries will potentially have the remainder, despite these countries comprising more than 85 per cent of the world's population.

 

Up to 40 per cent of the vaccine courses from these vaccine manufacturers might potentially remain for low- and middle-income countries.

 

However, this will depend, in part, on how high-income countries share what they procure and whether the US and Russia participate in globally coordinated efforts.

 

But the authors point out that even if all of these vaccine manufacturers were to succeed in reaching their maximum production capacity, at least a fifth of the world's population would not have access to vaccines until 2022.

 

"This study provides an overview of how high income countries have secured future supplies of covid-19 vaccines, but that access for the rest of the world is uncertain," they wrote.

 

"Governments and manufacturers might provide much needed assurances for equitable allocation of covid-19 vaccines through greater transparency and accountability over these arrangements."

 

In the second study, researchers based in China and the US estimated target populations for whom vaccines would be required, to help guide development of fair and equitable allocation strategies across the globe.

 

They found that target population sizes for Covid-19 vaccination vary widely by geographical region, vaccine objectives and the impact of vaccine hesitancy in reducing demand.

 

They point to evidence suggesting that around 68 per cent of the global population (3.7 billion adults) is willing to receive a Covid-19 vaccine, and say their findings "provide an evidence base for global, regional, and national vaccine prioritisation and allocation."

 

The findings illustrate the considerable scale and complexity of manufacturing, purchasing, distributing, and administering Covid-19 vaccines in a way that meets global needs, and does so equitably among nations and populations.