(AP) — Health officials and experts in Asia have welcomed U.S. plans to share 500 million more doses of the Pfizer vaccine with the developing world, but some say it would take more than donations alone to address huge vaccination gaps that threaten to prolong the pandemic. President Joe Biden was set to make the announcement Thursday in a speech before the start of the Group of Seven summit in Britain. Jaehun Jung of South Korea’s Gachon University College of Medicine says the U.S. donations may prove to be a huge turning point but could have come earlier. He says the extremely cold storage temperatures required for Pfizer shots would also present challenges for some countries. Inequities in vaccine supplies around the world are becoming more pronounced.