The USDA granted Dalan Animal Health a “conditional license for vaccination of honeybees against American Foulbrood disease caused by Paenibacillus larvae.”

As the NYT explains:

Before you start imagining a tiny syringe being inserted into a bee, the vaccine, which contains dead versions of the bacterium Paenibacillus larvae, comes in the form of food. The vaccine is incorporated into royal jelly, a sugar feed given to queen bees. Once they ingest it, the vaccine is then deposited in their ovaries, giving developing larvae immunity as they hatch.