How young can a child be, for getting coxsackie hand-foot-mouth disease?

Infants: Maternal antibodies likely protect newborns for the first 2-3 months if the mother had the hfm strains in her lifetime, but unprotected newborns may be susceptible to these human only strains. They may not rash out like older kids. I have seen hfm in kids as early as 6m.

Birth: If the mother of the infant is not immune to the varient that the infant is exposed to then the infant has no immunity and is at risk of the disease. Currently there is an unusual variant of the disease in the us and most people are at risk.