Some 145 million to 150 million doses of coronavirus vaccines could be delivered in the first quarter of this year to countries in the Covid-19 Vaccines Global Access (Covax) scheme - the first milestone in the initiative's plan to secure nearly two billion doses by the end of the year.
Covax is also in a position to buy spare doses from high-income countries, many of which have taken "multiple shots on goal" and purchased in excess of their needs, said Dr Seth Berkley, who heads the Gavi vaccine alliance, yesterday.
"Obviously right now, there's a little bit of a global vaccine panic, and so many countries want doses," he told a virtual discussion organised by the World Economic Forum (WEF) Davos Agenda 2021.
"And today, we're doing the best we can to move this forward."
Covax, which aims to distribute vaccines equitably around the world, is jointly led by Gavi, the Coalition for Epidemic Preparedness Innovations and the World Health Organisation.
It aims to roll out around 500 million doses in the second quarter of this year, and another 1.5 billion over the remainder of the year, Dr Berkley said. He added that the organisation is waiting for regulatory approval for certain vaccines, following which it will distribute them as broadly as possible.
Although it hopes that high-income countries will donate their extra vaccine doses, Covax is in a position "to buy them or to take a spot in a manufacturing queue, to make them available equitably".
"What's important is that those vaccines have a full shelf life, have the ability to be used in different parts of the world, (and) have been going directly from the manufacturers so that they've been handled properly and the cold chain is maintained," Dr Berkley said.
He estimated that high-income countries have, at present, secured over 800 million doses in excess of their actual requirements, with another 1.4 billion doses in options.
During the session on the logistics of rolling out a Covid-19 vaccine across the world, participants pointed out potential bottlenecks in delivery. For instance, vaccine doses are not the only things that have to be rolled out, said Ms Dorothea von Boxberg, Lufthansa Cargo's chief commercial officer.
"You also have to give the doctor additional material like syringes, so it is a big, big logistical effort to get everything in place and also keep the cold chain... for the vaccines."
On the bright side, logistics company Deutsche Post DHL Group said flights to distribute the vaccines can be easily ramped up once more doses are available.
"The whole industry can manage much more than what is currently needed," said Dr Frank Appel, its chief executive. "On our own, we are operating 250 flights a night. We can do significantly more."
The challenge is for local governments to work out last-mile vaccine distribution logistics, he added. For instance, if the plan is for doctors to administer the vaccine doses from roving trucks, then fewer refrigerators are needed.
"All these questions need to be answered by the local governments."
Another thing to look forward to is that the next generation of vaccines, which are likely to have less stringent storage and transportation requirements, are one step closer to hitting the market, Dr Berkley said.
The currently available Pfizer-BioNTech and Moderna vaccines were "quite expensive, produced in relatively small quantities to start with, and had some issues in terms of their cold chains". This made it more difficult for them to be distributed globally.
Now, there are "a whole range of new manufacturers", Dr Berkley added, with two major ones expected to move to the next stage in their clinical trials over the next week or two.