Surveillance of invasive pneumococcal disease and serotypes coverage of pneumococcal vaccines in the Czech Republic between 2007 and 2024

OBJECTIVE: This study presents the epidemiological situation of invasive pneumococcal disease (IPD) in the Czech Republic between 2007 and 2024. METHODS: The source of data for the study was the nationwide IPD surveillance programme, which started in 2008, 2007 being the pilot year of the programme. Surveillance data on the IPD were obtained by combining data from the National Reference Laboratory for Streptococcal Infections (NRL) and data from EpiDat and the Infectious Disease Information System (ISIN), respectively, always excluding duplicate records. RESULTS: Between 2007 and 2024, the total of 7,144 cases of IPD were recorded in the Czech Republic, with a total incidence of 3.7/100,000 population, varying in the individual years between 2.3 and 5.6/100,000. The age-specific average annual incidence over the entire period was at the following levels: children under one year - 6.1/100,000, children 1-4 years - 3.9/100,000, adults 40-64 years - 3.7/100,000, adults 65 years and older - 9.6/100,000. For the period 2007 to 2024, serotypes 3, 19A, and 8 were the most common serotypes detected in IPDs. In the 0-4 years age group, serotypes 3, 19A, and 14 were the most common serotypes; in adult aged 65 years and older, serotypes 3, 19A, and 22F were the most common serotypes. Over the years, there was a decline of serotypes included in pneumococcal conjugate vaccines (PCVs), with the exception of serotypes 3 and 19A, and an increase of serotypes not included in pneumococcal vaccines. Following the introduction of vaccination against pneumococcal diseases in the Czech Republic, the occurrence of serotype 4 initially declined; however, in recent years, its occurrence has increased. The percentage coverage of serotypes causing IPD with currently recommended pneumococcal vaccines in 2024 was as follows: PCV13 - 42.8%, PCV15 - 48.5%, PCV20 - 60.7%, PCV21 - 62.8%, PPV23 - 66.9%. The percentage coverage of serotypes in the Czech Republic by current vaccines is comparable to that in other countries; however, in the case of potential new vaccines, it is lower than reported in other countries. CONCLUSION: Between 2007 and 2024, there was a decrease in IPD morbidity in the paediatric population and an increase in IPD morbidity in adults aged 65 years and older. The data presented may serve as a basis for updating recommendations for vaccination against pneumococcal diseases by the Czech Vaccination Society. Given the serotype coverage of the individual vaccines, we recommend the use of higher-valent conjugate vaccines PCV15 or PCV20 in children, rather than PCV13. The development of pneumococcal vaccines is based on data from IPD surveillance programmes in countries other than the Czech Republic; therefore, the serotype composition of these vaccines may not fully correspond to the serotypes circulating in the Czech Republic. The development of new pneumococcal vaccines is ongoing. It is essential to continue detailed surveillance of IPD in order to update and optimize vaccination strategy against pneumococcal diseases in the Czech Republic.