Shipping a coronavirus vaccine around the world will be the "largest transport challenge ever", according to the airline industry.
The equivalent of 8000 Boeing 747s will be needed, the International Air Transport Association (IATA) has said.
There is no Covid-19 vaccine yet, but IATA is already working with airlines, airports, global health bodies and drug firms on a global airlift plan.
The distribution programme assumes only one dose per person is needed.
"Safely delivering Covid-19 vaccines will be the mission of the century for the global air cargo industry. But it won't happen without careful advance planning. And the time for that is now," IATA chief executive Alexandre de Juniac said.
While airlines have been shifting their focus onto delivering cargo during the severe downturn in passenger flights, shipping vaccines is far more complex.
Not all planes are suitable for delivering vaccines as they need a typical temperature range of between 2 degrees Celsius and 8C for transporting drugs. Some vaccines may require frozen temperatures which would exclude more aircraft.
"We know the procedures well. What we need to do is scale them up to the magnitude that will be required," added Glyn Hughes, the industry body's head of cargo.
Difficulties predicted in some regions
Flights to certain parts of the world, including some areas of South East Asia, will be critical as they lack vaccine-production capabilities, he added.
Distributing a vaccine across Africa would be "impossible" right now, IATA said, given the lack of cargo capacity, the size of the region and the complexities of border crossings.
Transportation will need "almost military precision" and will require cool facilities across a network of locations where the vaccine will be stored.
About 140 vaccines are in early development, and around two dozen are now being tested on people in clinical trials.
One is being developed by the University of Oxford that is already in an advanced stage of testing, although it was halted this week due to one participant becoming ill.
IATA has urged governments to begin careful planning now to ensure they are fully prepared once vaccines are approved and available for distribution.
Along with making sure they are handled and transported at controlled temperatures, security is another issue.
"Vaccines will be highly valuable commodities. Arrangements must be in place to ensure that shipments remain secure from tampering and theft," added IATA.
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