This month, the Cambodian government reported that two people there died of highly pathogenic avian influenza, or H5N1 bird flu, after being exposed to infected poultry. For people, the risk of getting infected is low, but outbreaks in animals have been rising worldwide, wiping out chicken flocks and wild bird populations. The virus is devastating to poultry producers, who are forced to slaughter infected flocks.

A growing number of countries are starting to vaccinate chickens against bird flu, while the United States and United Kingdom are still holding out because of uncertainties about immunization’s cost and effectiveness. Meanwhile, researchers in the UK have come up with another possible approach to