ABSTRACT
An important feature in most developing countries and other populations with high rates of GAS infection is the enormous diversity of different strains present in a community at any one time compared with low-incidence populations, and the rapidity with which these strains enter and leave even small populations (9-11). Over periods of just months, the profile of strains, as defined by emm type or multilocus sequence type, can virtually entirely change (10,12,13), which presents a significant impediment to vaccine development.
