The AMC mechanism should provide incentives to vaccine manufacturers to invest in large scale production capacity even as they develop new products and before full-scale trials have shown whether they work, GAVI's chief executive officer Seth Berkley told Reuters.
In return GAVI will agree to buy large quantities of vaccines at established and equitable prices to ensure initial doses are not immediately snapped up by rich countries.
"GAVI is worried about the low- and middle income countries," Berkley said in a telephone interview on Wednesday.
Around a hundred drug development teams worldwide, including institutions, biotechs and big pharma companies, are racing to develop vaccines against COVID-19 amid a pandemic that has infected more than 6.3 million people across the world.
Among front runners currently in trials are potential vaccines being developed by AstraZeneca, CanSino Biologics, Pfizer and BioNtech, Johnson & Johnson, Merck, Moderna and Sanofi.
GAVI is a public-private partnership backed by the Bill & Melinda Gates Foundation, the World Health Organization, the World Bank, UNICEF and others, which arranges bulk buys to reduce vaccine costs for poor countries.
"The worry we have is that unless we scale up production dramatically right now, and do that at risk, when the vaccines are available, they could be bought up by wealthy countries," Berkley said.
"We're trying to put together a facility that has global scope and that will work with manufacturers and help them scale up by saying to them: 'If you have a successful vaccine, we will buy it'."
Berkley declined to say which potential vaccines or manufacturers would be covered in GAVI's initial AMC proposal, but said more details on that may be released later this week.
"There are still issues being worked out," he said.
GAVI is due to hold a global vaccines summit in London on Thursday at which it is seeking to secure funding of around $7.4 billion to fund its immunisation programmes between 2021 and 2025. It says those funds will help immunise 300 million children, saving an estimated 7-8 million lives.