A commentary suggests that in an optimistic scenario, only a limited number of the more than 90 known serotypes would cause substantial disease, and current vaccine or one of higher valency would restrain most invasive pneumococcal disease. On the other hand, other residual virulent serotypes might continue to emerge with each new higher valency vaccine, until an effective universal pneumococcal vaccine or some other solution becomes available. Thus modelling of changes in pneumococcal carriage and disease after vaccine introduction, along with detailed characterisation of specific serotypes could help inform future choices of vaccine composition.