Public Defence: Anneke Steens

M.Sc. Anneke Steens at Institute of Basic Medical Sciences will be defending the thesis “A scientific basis for vaccination policies during a changing pneumococcal epidemiology” for the degree of PhD (Philosophiae Doctor).

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Trial Lecture – time and place

See Trial Lecture.

Adjudication committee

  • First opponent: Senior Epidemiologist irjam Knol, National Institute for Public Health and the Environment, the Netherlands
  • Second opponent: Docent Åke Örtqvist, Smittskydd Stockholm
  • Third member and chair of the evaluation committee: Professor Fredrik Müller, University of Oslo

Principal Supervisor

Department Director Didrik F. Vestrheim, Norwegian Institute of Public Health


Pneumococci are often present in the human nasopharynx (i.e. carriage) but can cause severe disease such as sepsis, meningitis and pneumonia. Children carry the bacterium most often and are the main transmitters in the population. Since 2006, pneumococcal vaccination has been part of the Norwegian childhood vaccination programme, which has led to substantial changes in the pneumococcal epidemiology. In 2011, a broader vaccine (PCV13) replaced the initial one (PCV7).

The aims of this thesis were to assess the impact of PCV13 on the pneumococcal carriage prevalence in children, on the incidence of invasive pneumococcal disease in the population including risk groups, and to predict how this would affect the public health impact of different vaccination strategies for risk groups.

We used data from nationwide health registers (the surveillance system for communicable diseases and the prescription register), collected nasopharyngeal samples from more than 2000 children, and reviewed international literature. Using statistical analyses we predicted the incidence of invasive pneumococcal disease in the near future and explored the public health effect of different pneumococcal vaccine strategies.

We found substantial protection of pneumococcal childhood vaccination for the entire Norwegian population, including elderly and medical risk groups, despite a small increase in non-vaccine type carriage and disease. This protection has reduced the preventive potential of PCV13 for risk groups, and the use of the polysaccharide vaccine (PPV23) in risk groups may therefore prevent more cases as long as children are vaccinated with PCV13. Broader and more effective vaccines and revised vaccination strategies may reduce the disease burden in risk groups further.

Additional information

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Published Aug. 22, 2019 5:15 PM - Last modified Aug. 27, 2019 11:52 PM