Covid-19 has sparked an unprecedented mobilization of researchers looking to create a drug that can stem the spread of the virus. Globally, drug developers are working on as many as 100 experimental vaccines. But as nations rush to ease lockdowns and restart economies, some countries seem to want to secure early supplies of a vaccine for themselves. James Paton reported on efforts to democratize international access to vaccines, and the dangers of creating immunization gaps.See omnystudio.com/listener for privacy information.