With Ireland's COVID-19 vaccination campaign due to start by early January, a new study has warned that some countries may be waiting until 2022 before they have access to any vaccines.

Researchers at the John Hopkins Bloomberg School of Public Health in the US analysed pre-orders for COVID-19 vaccines ahead of their regulatory approval by countries worldwide.

They found that by mid-November, a number of countries had reserved almost 7.5 billions doses of various COVID vaccines, which will be used on over 3.7 billion people.

However, the researchers noted that 51% of these doses will go to high-income countries, which make up around 14% of the world's population. Low and middle-income countries, which make up over 85% of the world's population, will have the remainder.

Furthermore, even if all of the vaccine manufacturers were successful in reaching their maximum production capacity, at least 20% of the world's population would not have access to COVID 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. Governments and manufacturers might provide much needed assurances for equitable allocation of COVID-19 vaccines through greater transparency and accountability over these arrangements," the researchers said.

Meanwhile, a second study carried out by US and Chinese researchers estimates that 3.7 billion adults around the world are willing to get the COVID-19 vaccine. They said that these findings "provide an evidence base for global, regional, and national vaccine prioritisation and allocation".

"Variations in the size of the target populations within and between regions emphasise the tenuous balance between vaccine demand and supply, especially in low and middle-income countries without sufficient capacity to meet domestic demand for COVID-19 vaccines," they added.

Details of both studies are published in the British Medical Journal.

For information on Ireland's COVID-19 vaccination strategy, click here.