Developing nations are at risk of being left far short of the Covid-19 vaccine supplies they need as richer countries secure billions of doses even before the drugs pass final clinical trials, according to health experts.
The U.S., the European Union, Japan and the U.K. have agreed to purchase at least 3.7 billion doses from Western drugmakers developing vaccines, according to announcements from the companies and countries in recent months. That tally includes options available for additional doses. China and India, two countries…