In recent months, Americans looking for eggs have faced empty shelves^[1] in their grocery stores. The escalating threat of avian flu has forced farmers to kill millions of chickens^[2] to prevent its spread.

Nearly 70 years ago, Maurice Hilleman^[3], an expert in influenza, also worried about finding eggs. Hilleman, however, needed eggs not for his breakfast, but to make the vaccines that were key to stopping a potential...