A pioneering genomic surveillance study has provided the clearest picture yet of the arms race between Streptococcus pneumoniae, the bacterium responsible for a range of illnesses such as pneumonia and meningitis, and the vaccines designed to protect against the most dominant types. A strain called GPSC10 was found to be a particular threat, due to its increased virulence, ability to transform its structure to evade vaccines and its resistance to several common antibiotics.