Quillay trees are rare evergreens found mainly in the South American country of Chile. And they are increasingly important to producing new vaccines. The native Mapuche people have long used them to make soap and medicine. In recent years, quillay trees, also known as quillaja saponaria, have been used in the processing of food and drinks. They have also been used to make a highly successful vaccine against shingles, a painful viral disease, and the world’s first malaria vaccine. Now, molecules extracted from the bark, or outer covering, of older quillay trees are being used for a COVID-19 vaccine. It is being developed by American drug-maker Novavax. Over the next two years, Novavax plans to produce billions of treatments of the vaccine for use in developing countries.