BOGOTA, Nov 10 (Reuters) - Colombia hopes to have supplies of a COVID-19 vaccine from Pfizer Inc or other drugmakers in the first half of next year, the government said on Tuesday, and is working on "ultra freezing" units in five cities to store the doses.

Pfizer and German partner BioNTech said this week their experimental COVID-19 vaccine, which requires ultra-cold storage, is more than 90% effective based on initial trial results.

COVID-19 has killed over a million people and battered the world's economy. Just under 33,000 people have died in Colombia, which held more than five months of national quarantine earlier this year.

"Colombia is working on the development of ultra-freezing in five cities," Health Minister Fernando Ruiz said in a statement. "Nevertheless, the mechanism that Pfizer is using for these vaccines includes ultra-frozen delivery until the point of application."

The vaccine, stored in "specialized boxes", can be used for an average of between 10 and 20 days once it reaches its application location, the statement added.

The government and Pfizer held a meeting to discuss freezing and transport, which will be supplied by the company, the ministry said.

Pfizer did not immediately respond to a request for comment, but has previously said it has detailed plans and tools to support vaccine transport, storage and continuous temperature monitoring.

Colombia, which provides 22 vaccines free of charge and will include COVID vaccinations under the same scheme, said last month ultra cold-storage vaccines could present distribution challenges.

Immunizing remote populations in the Andean nation's mountains and jungles sometimes requires transportation by river or on horseback, journeys that could prove difficult if extremely low temperature storage is needed.

Officials have raised similar concerns for countries in Asia, Africa and Latin America grappling with tropical heat, remote communities and lack of infrastructure. Even wealthier nations like Japan and South Korea say storage will be logistically complex.

Colombia initially wants to vaccinate 15 million people - more than a fifth of its population - who are older than 60, have pre-existing conditions or work in healthcare.

The global COVAX initiative will provide for 10 million people and the country is seeking the remainder in talks with drugmakers.

"COVAX is committed to delivering vaccines from the second half of 2021. With the bilaterals, Pfizer and the rest, we will seek to buy vaccines to have availability in the first half of 2021," Ruiz said.

Pfizer and BioNTech have said pending regulatory approval they can roll out up to 50 million doses this year and produce up to 1.3 billion doses in 2021. (Reporting by Julia Symmes Cobb; Editing by Tom Brown)