Since the late 1990’s British farmers have been vaccinating hens against salmonella following a crisis that sickened thousands of people who had consumed infected eggs. Amazingly, this measure has virtually wiped out the health threat in Britain. In 1997, there were 14,771 reported cases of salmonella poisoning there, by 2009 this had dropped to just 581 cases. About 90 percent of British eggs now come from vaccinated hens – it’s required for producers who want to belong to the Lion scheme. The remaining 10 percent come from very small farmers who don’t sell to major retailers.
In contrast, there is no such requirement for commercial hens in the US. Consequently, according to FDA data, there are about 142,000 illnesses every year caused by consuming eggs contaminated by the most common strain of salmonella. Only about one-third of farmers here choose to inoculate their flocks. Farmers cite cost as the main reason not to opt for vaccination –FDA estimates say it would cost about 14 cents a bird. The average hen produces about 260 eggs over the course of her lifetime.