Less developed countries in the Americas are not ready to handle messenger RNA vaccines, such as the one developed by Pfizer Inc, that need very low storage temperatures of minus 70 degree Celsius, the WHO's regional office said on Wednesday.
This could become a challenge for transporting such vaccines in countries that do not have the cold storage capacity. Pfizer recently announced its vaccine is more than 90% effective based on initial trial results.
(Reporting by Anthony Boadle; Editing by Chizu Nomiyama)
