Replacement

Serotype replacement means the replacement of the serotypes in the vaccine with serotypes that aren't included in the vaccine. In a vaccinated population the replacement has usually happenes fairly fast after the beginning of the vaccination program. Because of serotype replacement the vaccine against the desease has been less efficient than expected. Nurhonen and Auranen have built a model [1], that describes the mechanism of replacement in a vaccinated population. With the model it is possible to calculate estimates for the effects of different serotype combinations in vaccines against pneumococcal disease incidences in a population and find the serotypes that it would be most effective to add to current vaccinations in order to avoid invasive pneumococcus infections.