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The evidence presented in the article strongly supports the notion that serotype replacement has occurred in invasive pneumococcal disease in most populations and is caused by the vaccine. The recently introduced 13-valent vaccine has the potential to have significant and sustained effects on disease, particularly in developing countries. Serotypes 1 and 5, in particular, which are covered by this vaccine, are rarely carried but cause a lot of disease in many areas.
As a result, the elimination of these two specific serotypes is unlikely to be followed by substantial replacement. Although it is difficult to predict how the composition of NVTs will change after the introduction of PCV13, projections based on the invasiveness of the serotypes suggest that this new vaccine will result in additional reductions in disease incidence.