An experimental plague vaccine proved 100 percent effective when tested in a new mouse model for plague infection developed by scientists at Rocky Mountain Laboratories (RML), part of the National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health. The scientists developed their model to mimic the natural transmission route of bubonic plague through the bites of infected fleas. The flea-to-mouse model provides a more realistic test setting than previously used methods, enabling a better assessment of a vaccine’s ability to protect against a real-world challenge.