Summary of pneumococcal acquisition events by age category.

a Including 73 swabs for which two serotypes were identified.
b New acquisitions defined as acquisition of serotype not previously carried; reacquisition defined as acquisition of a previously-carried serotype.
c Household introductions classified as “unique” if the participant was the only one in the family to acquire the new serotype; “concurrent” if more than one individual acquired the serotype simultaneously.