Immune and strain surveillance of the Streptococcus pneumoniae: Tools to study the impact of pneumococcal conjugate vaccination

PhD ceremony: Ms. K.E.M. Elberse, 12.45 uur, Aula Academiegebouw, Broerstraat 5, Groningen

Dissertation: Immune and strain surveillance of the Streptococcus pneumoniae: Tools to study the impact of pneumococcal conjugate vaccination

Promotor(s): prof. H. Grundmann

Faculty: Medical Sciences

In 2006, the pneumococcal vaccine was introduced in the national immunization program in the Netherlands. The vaccine is administered to children in the first year of their life in a 2-3-4-months vaccination scheme, and an extra vaccination at 11 months. It protects against severe infections such as meningitis and pneumonia. The vaccine is directed against the 7 most important serotypes (out of 90) of the pneumococcus. In 2011, the vaccine was replaced by a vaccine that is directed against 10 different serotypes.
When someone is infected by a pneumococcus, or a person is carrier without symptoms, antibodies are produced in the human body. Using a new test, we determined the concentrations of antibodies against 13 of the most important serotypes in the Dutch population. The results inform us about the natural acquired antibody concentrations against the pneumococcus in the Dutch population before the introduction of the vaccine in the national program. The data showed no relationship between natural acquired antibody concentrations and the number of severe pneumococcal disease.
Since the introduction of the vaccine, a decline of the number of severe pneumococcal disease in children was seen. The selective pressure of the vaccine induced changes in the occurrence of serotypes, but does not yet seem to influence the genetic background of the pneumococcal population. Variants within serotypes seem to occur and these strains may avoid the vaccine immunity, but additional research should be done to elucidate this.