Epidemiology of Invasive Pneumococcal Disease in Czech Children under 5 Years of Age after Routine Immunisation.

ABSTRACT

BACKGROUND: The introduction of the surveillance of invasive pneumococcal diseases (IPD) in 2007 has helped to monitor changes in serotype occurrence in the Czech population and assess the impact of routine immunisation against IPD on the child population under 5 years of age. METHODS: Observational study of childhood IPD in the Czech Republic based on the state public health surveillance data comparing pre-immunisation (2007-2008) and post-immunisation (2012-2013) periods. RESULTS: In the child population there was an overall decline in IPD occurrence of 46.6% (95% CI 63.4-21.9) observed during the post-immunisation period. There was even greater decrease of 71.6% (95% CI 50.4-83.8) in vaccinated children. In the post-immunisation period, Prevenar 13 (PCV13) and Synflorix (PCV10) contributed to a vaccine-type IPD reduction of 95.4% (95% CI 67.0-99.4) and 76.9% (95% CI 36.0-91.7), respectively, compared to unimmunised children. The occurrence of 10 serotypes contained in both commercial vaccines also decreased in unvaccinated children by 61.4% (95% CI 14.5-82.6). However, a rise in the risk of non-vaccine and unspecified serotype acquisition by up to 153% was revealed in unimmunised children when comparing post-immunisation and pre-immunisation periods. CONCLUSIONS: The findings suggest a shift in IPD caused either by vaccine or non-vaccine serotypes between immunised and unimmunised populations of children, which could result in increased incidence of IPD caused by non-vaccine serotypes. Therefore, routine immunisation using only one vaccine with broader serotype coverage together with a higher vaccination rate could raise hopes of further decrease in IPD in the child population.