Any parent who has ever taken their child to a seemingly endless series of vaccinations armed with pacifiers, lollipops, and a pack of lies about how much it will hurt must have hoped that one day someone would come up with a better way to protect infants from infections. A few may even have looked on wistfully as the oral polio vaccine went down in one and wondered why all vaccines weren't that simple. Fortunately, scientists love their children too. For the past 15 years they have been looking for the best way to produce vaccines you can eat.

The original idea was simple. Genetically engineer an edible fruit or vegetable so that it contains a vaccine and feed it to children. Early pioneers started experimenting with carrots, bananas, tomatoes, soya beans, and corn. One team led by Charles Arntzen, the US based grandfather of edible vaccines, made it all the way to phase I human trials with potatoes engineered to produce harmless antigenic proteins from enterotoxigenic Escherichia coli, Norwalk virus, and hepatitis B virus. In a series of elegant experiments, volunteers who ate the potatoes mounted a limited immune response to all three.1 2 3

Now though, the science has moved on, and along with it the aspirations of Professor Arntzen and other enthusiasts. Edible vaccines have grown up during the past five years, and whole fruit and vegetables are off the menu. Scientists now see genetically engineered plants not as food but as an efficient production system for antigenic proteins that can be processed into pills or capsules containing fixed reproducible (and marketable) doses.

Earlier this summer, a team of scientists from Japan reported preliminary success …