Works in Progress The first vaccine was a lucky accident. Now we can design new vaccines in weeks, atom by atom.
In 1796, when Edward Jenner developed the first vaccine, against the smallpox virus, no one knew what viruses were, let alone connected them to diseases.
Many believed Jenner’s vaccine worked because it depleted the body of the specific nutrients the disease needed to thrive. In reality, his concept worked because of the good fortune that cowpox infections provided cross protection1 against smallpox. It would take almost a century to work out how to develop vaccines against other diseases. Stocks of Jenner’s vaccine would die out repeatedly, and needed to be rederived from scratch many times. Keeping a vaccine alive in the nineteenth century was grueling, requiring arm to arm chains of transmission2 just to preserve the material.
The process improved slowly. In the 1840s, doctors invented a method to grow the smallpox vaccine virus more safely and reliably on the skin of calves.3 The 1890s saw a method to keep it from spoiling quickly by mixing it with glycerin, and in the 1940s, scientists learned how to freeze-dry it to survive heat and long journeys. In the 1960s, the bifurcated needle, with a forked tip that could hold a tiny drop of vaccine, made it possible to use only a quarter of the usual dose and helped scale up vaccination. Technological innovations like these made it possible to eradicate smallpox worldwide.