We investigated enterovirus A71-associated hand, foot and mouth disease in Vietnam and found that, after replacing subgenogroup C4 in 2013, B5 remained the leading cause of this disease. In contrast with previous observations, this switch did not result in an explosive outbreak, and B5 evolution was driven by negative selection.
Keywords: Enterovirus A71; Picornaviruses; Vietnam; hand foot and mouth disease; phenotypes; viruses.