In the quest to develop shots against Covid-19, researchers have overcome challenges that typically make vaccine projects stretch across years if not decades. Assuming one or more of their experimental vaccines proves safe and effective in late-stage trials — a huge feat in itself — drug companies and health officials will next face a whole new set of obstacles in their effort to deliver the shots widely around the world. Preparations for vaccinating the planet’s 7.8 billion people are already underway.
Getting the Green Light
Typically, a vaccine must show that it works in trials involving thousands of volunteers before regulators consider permitting its use outside of research. While China and Russia are using special regulatory provisions to deploy Covid vaccines before they’ve undergone full testing, nine U.S. and European companies that are in the forefront of the